I worked on this family a handful of years ago. I don't have my notes handy now, but was not able to make all of the connections I was hoping for.
There are several markers in the cemetery at Llanddeusant Parish church - I have some photos I'm willing to send you. One of the descendants of LEWIS of Panthowel line married into my family (Jeffreys) living at Llwynyfron, Llanddeusant since the 1700s - and still living there today.
An old gentleman, David "Dai" Lewis, at Llangadog, helped me a bit as this was his line, also. He gave me a couple of old Victorian photographs on one of my visits.