I am somewhat perplexed by your post.Frederick ROPER, a very early Methodist Minister, was the ROPER who settled in Hyde County, North Carolina.He is enumerated in the Census there in 1800, 1810 and 1820.
Frederick ROPER is shown to have died on 14 Apr 1820.I do not have a ready reference for that date of death, but believe it to be reasonably reliable.
Frederick ROPER was married to Sarah GIBBS.
Sarah Gibbs ROPER appears in the U.S. Census for Hyde County, NC, in the 1830 and 1840 enumerations.Secondary sources show Sarah Gibbs ROPER to have died on 14 Apr 1850.
I see no Sally ROPER in the early Census data.
The 1800 Census record shows:
United States Census -- 1800 Hyde County, North Carolina
Source:Year: 1800; Census Place,Hyde,North Carolina; Roll:34; Page:375; Image:22; Family History Library Film:337910.
There are two females age 26 to 44 (b abt 1756-74).One of these seems likely to be Sarah Gibbs ROPER.Frederick ROPER is also shown to be in this age range.The identity of the second older woman in this household is unclear.Three females are shown to be age 10 to 15.One male child is under age 10.
In 1810, Frederick ROPER appears in the Census as "Fredrik":
United States Census -- 1810 Hyde County, North Carolina
Source:Year: 1810; Census Place,Hyde,North Carolina; Roll:40; Page:125; Image:0337913; Family History Library Film:00430.
The older female has seemingly died or left the household.Both Frederick and the older female, presumably Sarah, are shown to be in the same large age range, but the passage of a decade still allows us to narrow our estimate of their ages.They are still shown to be age 26 to 44 (b abt 1766-84), but read in conjunction and combined with the 1800 Census data, we get a narrower range of (b abt 1766-74).
In 1820, the enumeration shows a Fred ROPER:
United States Census -- 1820 Hyde County, North Carolina
Source:1820 U S Census; Census Place,Hyde,North Carolina; Page:257; NARA Roll:M33_83; Image:180.
Now, Frederick and Sarah both appear to be age 45 and over (b bef 1776).Combined with the information in the prior two Census enumerations, this suggests only that the 1820 data is consitent with the earlier information and that the best estimate is still (b abt 1766-74).
It seems most likely that Frederick is at the upper end of that age range, since he was admitted on trial as a Methodist Minister in 1790.It seems to me that it is most likely that he was already at least age 20 by then.In my view, a reasonable inference as to Frederick's DOB is probably (b abt 1766-70).The date often shown in ROPER family history files is 1765, which is quite close, yet inconsistent with the actual data.It seems likely that careless or dishonest ROPER researchers have simply ALTERED the date to fir this Frederick into a fraudulent lineage they have invented for which no supporting data has as yet been discovered.
Some ROPER genealogists have even created a fictional Richard Frederick ROPER to justify connecting this Frederick to earlier New Kent data.There is NO EVIDENCE that any such ROPER ancestor ever existed, but this hasn't discouraged thousands from claiming descent from this fictitious, fraudlent invention.
Both a Robert HOPKINS and a Henry HOPKINS appear on the very same Census page with Frederick in 1820.
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As aforementioned, Sarah again appears in the 1830 enumeration.John W. ROPER appears within the adjacent record.
United States Census -- 1830 Hyde County, North Carolina
Source:Year:1840; Census Place:,Hyde,North Carolina; Roll:362; Pages:78, 81; Images:827, 833; Family History Library Film:0018094.
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"Sally" is a nickname for Sarah.It would be my expectation that Sally ROPER in the 1820 record would be Frederick ROPER's wife "Sarah".
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Frederick and Sarah Gibbs ROPER's third child is shown in secondary records to be Sarah Ann ROPER.She is shown to have married Ambrose GIBBS.She might therefore be a candidate to be another "Sally ROPER".
I have some copies of other primary records for this family in storage.I will try to find them.There are actually quite a few extant records about the ROPERs in Hyde County, so I think that with a little effort you ought to be able to find some answers.
On balance, I think that the elder Sarah Gibbs ROPER is NOT a candidate.A child or grandchild of this couple might be.You haven't durnished sufficient other genealogical details to reasonably focus a search.