Hi You may find that Massachusetts is the easiest of all states for finding records.I have the three volume set of Sandwich vital records and I can send you what is found in there if you want to contact me privately, and I think I can supply somewhat more than that.I believe you will find that all the lines from Phebe back will be Cape Cod families going back to immigrants in the early 1600s.Probably almost all of the people in these lines should be fairly easy to find and document.
One of the entries is on page 404 of the published VR and from page 285 of the original record book kept by the town clerk.It has the children of Thomas Swift Ju[nior] and Temperance [the term junior then did not imply a relationship, only that there was an older man in the area covered with the same name).They are Phebe F, b. May 19, 1818; Mary Ann, Apr.16, 1822; Thomas C., Feb. 23, 1825; Seth F., Jan. 28, 1828; Temperance, Sep. 24, 1830; Eliza, Aug. 30, 1834; Sarah Delia, sep. 11, 1836; George Washington, July 4, 1839; Abby, Dec. 16, 1841.
The birth date for Phebe is 1818 in the record book, and 1817 on her grave, as I guess I mentioned before.The marriage records for Thomas and Temperance are 1. on p. 298, Sep. 27th, 1817 the intentions were entered, and Oct. 23, 1817 (p. 358) they were maried by Benjamin Burgess, Esq.From the VR note it sounds as though the grave may not be extant, and the record is from the early 1900s.It may be that the stone was obscurred even then or someone just made a mistake, but 1818 seems a more likely date.
Send me an email if you'd like me to see what I can find.