hi topsy yes i have quite a large tree for the generations under thomas and hannah briant.
a couple of things; i note you have put the 1765 date of birth to thomas and also you have his parents. Unless you have some proof or family lineage perhaps to say this is correct then i would question it. I have 3 thomas perry's around that age and area and have been unable to allocate the birth to the right one, and equally if you allocated the parents to a thomas perry, they may not be right either.
From what i've found, i've got the william and eliz hitchcock and their family, but the only child i've been able to follow has been their son william. It's true they have a thomas bn 1765 which might be the husband of hannah briant, but he could also be the husband of sarah bristow or ann swatton. There is another possible bn at wilsford in 1773.
So i've got a little perry island of wm and eliz plus their family, and then another large perry island of the briant perry's but i haven't joined them up without any proof. Have you just started your tree and are working your way back through the sources?
If you can either get on ancestry and look at the briant part or if i can work out how to do it i might be able to do you a gedcom of that part of the tree??
In honesty i really haven't gone through their family with a fine tooth comb as they just haven't linked up with mine yet, but they are most likely related at some point. You could join wiltsfhs and ask them if they can shed any light on the thomas perrys and the briant line.
regards