Just had a peek ... biggest will so far. I can't see that this is the will of 'our' Thomas Davies. The property is Tythin Strygos, the phrase, "large and ample manor, (sic), manner" is a common phrase used in wills, (there is another one at the bottom of the page), and is the equivalent of, "enjoy". I see at least another 4 properties mentioned, (2 in Llandewi) but there is no mention of Bryn Issaf or anywhere that we know of that connects to the Richards family. This includes the names of others mentioned in this will, (except for the Richard David). There appears to be some argument between the parties regarding the will. Someone else owned some of the property that was bequeathed, etc. There is no mention of a wife or children either and just a 'nephew' to indicate that he had a sibling.
My searches have produced wills as follows
Thomas Richard, 1676 Bond, of Lledrod. Wife, Margaret Thomas, Bonder is John Thomas.
David Richard, 1688 will. Son, Edward David, Dau' Hannah David, sister Mary Richard.
Thomas Richard, 1677 will. Sons Richard, Morgan and David Thomas.
Richard Evan, (son of Evan Richard, dec.), 1767 will. Bequests to uncle, Morgan Richard,
Elizabeth and Sarah Richard, aunts and Morgan Owen, Brother.
David Richard, 1775 will. Lledrod.Brother Lewis Richard.
This list is a good example of how patronymics can muddy the waters for us researchers!
Regards, Peter.