Here's some sources for Margaret Oldsworth that show she is not the immigrant.
N.B. The Gloucestershire Archives have made their records freely available during the pandemic, so Baunton & Cirencester registers, some wills etc are currently browse-able on Ancestry without a sub. (There doesn't seem to be a Nicholas in that family.)
See on opposite page for continued burials in Cirencester including Margaret, Widow, in 1636.
(As an aside, I think the 1622/3 burial of Robert George Esq on that page is probably not Margaret’s husband, but his cousin (son of Christopher) who mentions John George the eldest son of his cousin Mr. Robert George in his will (sounds like Mr. Robert is still alive at this point.).)
George of Baunton also on the 1682 visitation – available on Family Search.
Margaret is also apparently the mother of John George of Watertown on Wikitree - but this is her real son John:
Robert & Margaret (& sons John & Samuel) mentioned in 1622: (she married Nicholas in 1605 so bigamy afoot!)
Margaret's brother, Arnold, did migrate to Virginia, but wasn't there long before he died. He doesn't seem to have left any descendants there, his children were all grown before he left & they stayed in England.
I know Jack asked for sources for Nicholas’s wife Margaret. But I think he probably already knows there aren’t any coming any time soon. Did Nicholas even exist, let alone Margaret? See Nicholas George who died in Lancaster (George -631) who also had a wife called Margaret.
The other Nicholas (George-631) been given a birth in Writtle* but the tree for George-631 also goes back to the Georges of Baunton. (Incidentally, the Georges apparently rented out Baunton until well into the 1600s, so earlier generations are unlikely to have been born there (but the register for Baunton only starts in 1620s anyway.)
(*Writtle birth for Nicholas due to Waters & his ‘Virginia Gleanings in England’ - a will for Humphrey Cole of Tillingham who had a son William in Virginia and a son-in-law called John George, Yeoman of Writtle, (who wasn't in Virginia) is transcribed there. Other trees have this John as father of Nicholas, or father of John George of Maryland, or John George of Maryland as husband of a Margaret Cole and brother of Nicholas etc; but George-631’s tree has mutated. (Humphrey Cole’s daughter is not named – we don’t know if she was called Margaret.)
The Nicholas George & Margaret Saward marriage also has different dates on different trees. It may be based on this: https://www.familysearch.org/ark:/61903/1:1:NLCL-2QL (original is on image 134 of film.)
There are all sorts of permutations of Writtle & Baunton roots all over the internet; even a couple that have Margaret Oldsworth’s grandson, John George M.P.’s son, Robert going to New England & becoming the father of either a John or a Nicholas (or both) – Robert died as a child. (As did all of John George’s sons, leaving his daughter Elizabeth as his heir, as is shown in sources above.) Which leaves me with the impression that the roots of all these Georges are actually unknown.
Poor old Margaret Oldsworth should really be reunited with her real family & disconnected from Nicholas & the kids.
Does anyone know if there really was a Nicholas George of Massachusetts?