I am sorry that Cousin Remi's book has no such Marriage, and neither he nor Jette list a "Nadreau", but only a Nadeau. However, Robert Quintin, in his book of "dit" names does show a "Nadreau dit Nantais", so possibly some Madeau added the "R" and the dit name.
Also Jette, who published a "Dictionary" of all immigrants from France to Canada from about 1600 to 1730, does not have a "Marachan". Do you believe that this is some variation of "Marchand"? If you do, then I suggest that you contact Remi (by clicking on his name here on the forum).