These Johnsons were from Sharon,Massachusetts or were baptised there.
John Johnson and Sarah Swift were married Mar.13,1755 in Sharon.Their children were:
Johnson ancestry don't know,but Swifts I'm familiar with..
Sarah Swift's parents were Job Swift and Sarah Blackwell.Job's parents were Jirah Swift and Abigail Gibbs.Jirah Swift's parents were William and Sarah___.There's two more Williams.
Swifts old New England family.
See "The ancestry of Ezra Otis Swift..." on HeritageQuest. Land dealings of these Johnsons see The Mayflower Descendant Vol.48 No.1 p. 208.The Swifts and relations show up in various places including The Register of the New England Historical and Genealogical Society.
Hope this helps.Mike.