Hi Roger,
I've just had a quick look at the will of Hugh Rice dated 1767. The executors were his wife, Gwen and his eldest daughter, Mary. It looks as if Mary was married to the ubiquitous Thomas Richards and they are both seen to sign off on image 2 that you mentioned.
A surprise half way through is that Hugh Rice, Cleric, had a son, Hugh Rice, Cleric.
In the 1746 Indenture that names Jane Morgan (widow), and Edward Richards, Schoolmaster in a transaction involving Bryn Perfedd, the witness is Hugh Rice, Cleric. In the final accord Thomas Richards is a "Gent". The endorsement to this Indenture is made by Hugh Rice, Cleric.
Witnesses to his will are David Williams, Edward Richards and Roderick Lewis, Cleric.
In an Indenture of 1756 involving the same property, (Bryn Perfedd), the witnesses were David Richards of Ffosybleiddiaid, David Williams and a Thomas Davies of Wernvelen.
(Do we know who Thomas Davies was? Perhaps a link to the Rev.William Davies).
The 1722 Indenture is the best indicator that we have that there was a Thomas Richards at Bryn Issaf at that time and we more or less placed him as the son of David Richards of Llandewi Brefi. Perhaps we can link William Davies, the next owner of Bryn Issaf to the Rev. Thomas Davies and Daniel, his brother, or to the mystery Thomas Davies of Wernvelen.
Yes, it's good to be home again!