That Abraham and Jeremiah Marston knew each other is indicated in the "Index to Land Petitions: Original Series, 1783-1918", at the Provincial Archives of New Brunswick site which indicates that both, together, petitioned for land in what is now Carleton Co. in 1819. This petition is indicated as being on microfilm F-4184; which should be obtainable by interlibrary loan.
There is also Jeremiah Masten petitioning in York Co. in 1784 and 1785. (Carleton Co. was part of York Co., so this may be the same general area.) In 1784 (on F-1024) Jeremiah Masten is indicated as a member of the British American Corps; a Loyalist, military unit. In 1785 (same microfilm) Jeremiah And Abraham Masten petition with others as members of the King's American Regiment.
Abraham Masten petitions (F-1027) in Saint John Co., in 1785, with others
There was also a John Marsten petitioning for land in York Co. in 1785 (F-1027.) Possibly the John Masten who d. Portland Parish, Saint John Co., NB JAN1830 age 88 years (b. ca. 1742.) Sgt. John Masten was in Capt. William Fowler's company of the Loyal American Regiment. See:http://www.royalprovincial.com/Military/Musters/LoyAmRegt/la...
Judging from the other surnames (Fowler, Weekes, Clarke, Wright, Griffin, Maybee, Hicks, Lounsbury, Searles Ackerman, Cornell, Craft, Brundage, Brewer, etc. (to give some of them their usual spellings) most were from NY, many from Westchester Co.
Looking at a similar database for land grants, Jeremiah (210 acres) and Abraham (205 acres) Masten were amongst grantees in Woodstock Parish 22AUG1787. (F-16302.) The size of the grants suggest Loyalists, private soldiers, probably married with a few children.
is mentioned the grave of:
= Mary w/o Jeremiah d. 7 May 1864 ae 75 yrs
is indicated that York Co. has probate records for:
Marsten / Abraham / Canterbury / 1888
Marsten / Benjamin / ... / 1794
Marsten / Edward Lawrence Wetmore / Southampton / 1947
Marsten / Ezebiel / Canterbury / 1899
Marsten / Frederick K. / Canterbury / 1936
Marsten / George / Southampton / 1918
Marsten / Ila D. et al, Guardian Papers / ... / 1903
Marsten / Isaac Wesley / Canterbury / 1897
If your goal is to establish a connection between Jeremiah and Abraham, then the petitions may be useful. As it stands, it appears very likely that they were related; and is certain that they knew each other. Even if as at:http://www.nbgs.ca/firstfamilies/FAMILY-C-2006.pdf
Jeremiah is given as b. England. That they lived close to each other is indicated at:http://www.beaglz.com/francais/JG6.pdf
where, 18MAR1786, Jeremiah and Abraham Masten live on Blocks 4 & 5 (presumably in what is now Carleton Co.; but possibly in York Co.) Block 4 was in Prince William (to the King's American Dragoons) and Block 5 was in Queensbury, to the Queen's Rangers. Queensbury is in present-day York Co., and I think Prince William is as well; but both are close to Carleton Co. The way Jeremiah and Abraham sign their names is very similar, suggesting a common teacher (i.e., a parent.) I would go so far as to guess they were brothers. There is also an image of a list of grantees on Block 4, in which I seem to make out sergeant Jeremiah Masten, a single man 5AUG1785. Further down is an image of part of a cadastral map indicating that Abraham (Lot 43, 205 acres) and Jeremiah (Lot 42, 207 acres) lived side-by-side. this is likely the 1787 grant. These, and other considerations, suggest the two were immediate family, but not father and son; therefore brothers.
It is suggested that Jeremiah, s/o Abraham, was of English ancestry. Exactly what is meant is not clear, and why the distinction is necessary is also not clear. It seems rather unlikely that any member of this family ever saw England. The indication is that Abraham, as was Jeremiah, was in 1783 a young adult, unmarried, arrived with a Loyalist regiment.
I would suggest, then, examining the microfilms indicated above. Petitions often indicated places of origin, service and circumstances. It may be that at least similarities between Jeremiah and Abraham would make the concept that they were brothers sufficiently tenable as to form the basis of a working supposition.