Yes to 1701 and 1727 Wills. Yes to indenture that shows David as son and heir. No to the connection to David of Ffosybleiddiaid.
D.D.1460.Indenture, dated 1 Aug. 1769, being a lease for a year (so that a grant by release might be made) from David Richards of Strygosfawr in the parish of Lledrod, CO. Cardigan, gent, (son and heir of Thomas Richards of the same place, gent., deceased by Magdalen his wife) to James Lloyd of Mabus, Cardigan, esq., of messuages and lands in the said parish of Lledrod, called Strygos otherwise Strygos- fawr, and Twyn y rhose, and late in the tenures of Magdalen Richards, David Richards, Richard David and Thomas Jones. Witnesses : Wm. Lewis; David Jones; Richard Philipps.
This indenture shows that Thomas took over Strygosfawr when David (his brother) moved to Ffos in 1756. It shows David giving up the tenancy, (1 year's notice), of Strygosfawr in 1769 and this, I presume, is the result of Thomas' decease.
David of Ffosybleiddiaid had 2 children that I know of. David of Tynllan and a Daughter, Elinor. Knowing the family traits, I'm sure that he must have had other children not yet identified.
I see that Joseph, the son of Jane and Owen Davies was unmarried. You may remember that he was bequeathed Ynysberfedd in the Rev. Edward's will of 1833. He continued to live there until his death in 1872. Living with him was his nephew, + wife+5 children and 2 servants. This shows that Jane and Owen also had a daughter, (Jane), married to a John Lewis. As soon as the females change their name on marriage they are invisible unless, like the item in your link, they are shown with their family name plus a residence reference.
regards Peter