Hi, Kietta! There are more questions in your query than you actually ask; but I'll attempt a rational answer. Part of the difficulties are the various options.
The first consideration is which country you live in. Many countries have Heraldic Authorities in which personal arms have protection under law, and using another's can be, at best, extremely embarassing. This one reason why these authorities were created; for the orderly and proper usage of armorial bearings. These include (and as a vexolligist, your husband may know this) national, provincial and state flags. The USA does not have a specific authority for personal arms, but it does for military and government arms. Flags of organized governments are generally covered in the laws of that government. There are armigerous persons in the USA with legitimate arms, and some of them are wealthy enough to make things difficult for anyone imprudent enough to use them.
Second, the question arises as to what it is you want. Do you want a coat-of-arms, personal symbol, corporate symbol (which can be copyrighted or trade-marked), etc.? The advantage of a coat-of-arms is that, by tradition, its elements can be used as a seal or flag or other symbological representation. In fact, grants-of-arms can specifically authorize a flag or banner.
Assuming you want a coat-of-arms, and assuming you live in the USA, I have no difficulties with the assumption of personal arms. The two caveats are, you should familiarize yourself with Heraldry to facilitate a reasonable design, one that would not be regarded as being silly; and you would be bound by honour, if nothing else, to make an effort to assure that you did not replicate another's arms.
There are three ways to acquire arms:
1. Inherit them.
2. Be granted them.
3. Assume them.
In the first case, you should make an attempt to ascertain as to whether an ancestor had legitimate arms. If there was such an ancestor, if you can prove line-of-descent and if that line-of-descent was in the male line, it is generally assumed you have a right to a coat-of-arms. Not the same one, necessarily, but similar. The catch is, you have to prove the line-of-descent.
In the second case, you have to apply to the appropriate Authority. As a rule, they require a pedigree; that is, an attempt on your part to trace your ancestry, with the appropriate evidence. The Authority is required to determine as to whether you might be entitled to arms by right of descent, hence they need the information. They also need a reason to grant arms. A grant of arms can be made on the basis of accomplishments, community service or the memorialization of ancestry. A grant can be refused if it is deemed that you are unsuitable to bear arms, as arms are a mark of honour. A disreputable person would not be considered honourable. In most cases, an average, respectable citizen would not be denied. Also, there will be fees. These fees are not particularly cumbersome, but will eventually run to several thousands of dollars.
The third case is a reversion to the original status of arms. Anyone with pretensions to social rank or title or land ownership (essentially anyone capable of affording armour) would adopt personal ensigns to identify themselves. My opinion is that a nation in which personal arms are not controlled by a Heraldic Authority is in this primitive state, and that assuming arms is a legitimate means of acquiring them. The difficulty is the limited protection under law. (You could always challenge someone who uses your arms to a duel; maybe.)
The next factor is that you should not choose a coat-of-arms as husband and wife, nor attempt a 'family' coat-of-arms. You are an individual, and have different ancestors than your husband, and should be represented by your own armorial bearings. In Canada, a lady can be granted personal arms. In the USA, without an Heraldic Authority, the matter is governed by custom. That custom is that a lady does not bear arms. She might, as a dowager widow, display her husband's arms on a lozenge; or she might (as an armorial heiress of a father who had no sons) display her father's arms. In the latter case, the right to her father's arms are transmitted through her to her sons. Regardless of this custom, I feel that ladies (at least nowadays) have as much right to assume arms as any gentleman. The question as to whether those arms should be displayed on a shield or lozenge is a matter for debate elsewhere; but I would expect that it would be a matter of choice. They key point here is, do not design your arms as husband and wife, but as individuals. To represent your marriage, those arms can be impaled. Your eldest son (or child as the custom will become) would inherit both, quartering those arms.
Before I forget, it would not be proper to use a flag as mantling. Particularly if it was a national flag. Not unless you were the sovereign of that nation, or the right to do so had been specifically granted as an augmentation by that sovereign. Flags are part of the armorial bearings of a nation; and where there is a sovereign, of that sovereign. Even in the USA, usage of the flag, Seal of the President, etc., as armorial bearings are protected by constitutional law. There are exceptions, and elements of a shield have been incorporated into the mantling (not uncommon in Germany I believe); but, for simplicity's sake, if for no other reason, the colours for the mantling should be determined by the major colours of the shield. Usually, one is a metal (or/gold/yellow and argent/silver/white.)
So far, I have conjectured that you and your husband have designed, your own personal arms. Then, you have impaled them onto one shield to reflect your marriage. In these arms you may have incorporated elements reflecting a tradition of haute cuisine. Perhaps, if you are Cordon Bleu, even the ribbon of that society. Exactly what those elements should be, I am at a loss to suggest. Perhaps as a crest a demi-chef clad in kitchen whites? Simplicity and taste are important here, so the matter should be considered carefully. Certainly one's arms should reflect heritage, name and accomplishments. Since this is a tradition of several generations in your families, it certainly should be incorporated.
In that regard, using elements of another person's arms, where ther surname is the same, is not inappropriate if there is a reasonable belief of descent from that person. In my own case, the name, Murray, exists in Scotland and in Ireland. Scottish Murray arms and Irish Murray arms often exhibit the stars associated with the name, (as some Irish Murray's presumably came from Scotland), but there are two, specific and different origins of the name. Perhaps a better example might be Smith. Not all Smiths are related simply on the basis of their surnames. It would be inappropriate to base one's arms on another's simply because of a surname, but reasonable if there was an adequate reason to believe there was a line-of-descent from that person. I emphasize line-of-descent as, if John Smith was granted arms, this does not mean that his brother, or his brother's descendants, have any particular right to those arms. The opposite, actually.
There are societies in the USA where you can register such personal arms. In particular, there is the American College of Heraldry at:
Check under 'services'. Examine their web site carefully, as this organization (assuming you are resident in the USA) may be very helpful. Registration with them probably will not give you much legal protection, but may establish at least a copyright.
Alternatives to petitioning for a grant of arms, or assuming arms, would involve corporate arms. For example, you form a family association and that association applies for a grant of arms. One difficulty is that all members of the association use the same arms, there is no distinction of individuals. Another difficulty is that it would require incorporation, filing of annual reports, AGM's, etc., as required by the incorporating government. Such arms could be trade-marked, and have legal protection. A similar corporation could be a business; but when the business ceases to exist, so do the arms.
Amongst the ancestral nations you mentioned is Germany. Things are a bit different there. Arms are associated with surnames, and crests determine families. I have a difficulty with this, as, again, the individual is not reflected. There is an Heraldic Authority (sort of) but the actual application is 'farmed out' to private firms licensed to practice Heraldry. A very unsatisfactory situation from my point-of-view. (See my posting # 2718 at this forum.)
Another option to consider, assuming you wish to petition for a grant of arms, or assume arms, is that you might do so, not on your own behalf, but on your father's (if still living.) In Canada, a grant of arms can be made to an ancestor (even a deceased one of several generations) thus allowing all descendants to petition for their own grants based on the original. If your husband assumes armorial bearings, custom allows your sons (and daughters in Canada) to inherit versions as their own. If you assume arms, your children would quarter them with your husbands. If you assume arms for your father, and you have brothers, custom dictates that you do not transmit arms to your progeny. This patriarchial formality is beginning to disappear, and I would overlook it; opting for the Canadian custom where daughters inherit as well, with a system of cadency marks for daughters. an assumption/grant of arms for your husband, alone, does not allow his brothers (or sisters) to inherit them. If a father (or even grandfather) is the original grantee, then the matter is different. The difficulty is determining how to difference those arms (only the eldest son inheriting the un-differenced arms) to reflect the individuals.
As to using armorial bearings in genealogies as 'family' arms. This is a very unfortunate custom. Especially as those arms usually have nothing to do with the family under consideration; except a similar surname. I have seen the arms of Sir Isaac Newton assigned to a Newton in early Virginia. The presumption is ludicrous. Arms, whenever possible, should be identified by the present owner; or at least by the original grantee; or (if the only option) by known owners. Some person are perplexed by the variety of bearings attached to a particular surname. They do not seem to understand that a son's arms (second, third, etc. son) is necesssarily different than his father's; and that their sons will also have different arms. Because the differences are often slight (marks of cadency, etc.) the individual nature of the arms seems to escape them. If you assume arms, and have them registered, identify them as YOUR arms, with the date of registration and the society with which they are registered. If you achieve a grant of arms, identify the date and granting authority. Anyone with a smattering of Heraldry will recognize the improper usage of arms as the pretentious nonsense it is.
Hope that helps a bit.