The last property transaction I can find for Anne Griffith is in August 1724, and she is back at Vrondeg (recorded as Vron Deg so tricky to find). North East Wales Archives DD/CP/659.
Edward Griffith is still at 'Frondeg' in 1747 when he leases two messuages in Bersham and one in Esclusham. NEWA DD/PP/240,
I am told that according to A.N.Palmer (‘13 Townships’, Bersham p.79, para 64) Edward Griffith son and heir of Anne was at the large house called Pen-y-Gelli by 1752 according to a rate book.
So we seem to have a continuous thread of Griffith occupation in the immediate area. However there is a lot we don't know. The Edward that married Sarah was a widower, so who was he married to before - presumably a childless relationship as Elizabeth is his only heir? Finding this marriage might help decide his age. It seems very unlikely that the Edward that married Sarah in 1778 should be the same Edward, son and heir of Anne, in 1708.
Steve