My final contribution on all of this, I think:-

All the people you have on your tree "lift2" who were born in the 1750s and 1760s are listed at familysearch.org as baptised at Hubberston, but with no parents mentioned. HOWEVER, that site says the images are available at FMP - and so they are - and ALL the images say these people are children of William and ELIZABETH Lifton - just like the William baptised in 1758.

So the tree as it stands is definitely wrong: the top line should be William and Elizabeth, the next line should be their children including the William born in 1758.

What is still missing, as far as I am aware, is proof that the William born in 1758 married Mary Smith (at whatever date) and therefore was the father of your Richard baptised in 1788, and Mary, and another William, all listed as children of William Lifton and Mary (formerly Smith).

The William who married Martha Lewis in 1785 MUST be a red herring, because William and Mary had their daughter Mary baptised that year. Also the William who married Martha is described in the parish register as a WIDOWER. Perhaps he was the one born abt 1723 who died in 1796 - it might have been two old folks getting married for convenience.

IF the William born in 1758 was the one who married Mary Smith, he must have lost her (or left her) before he took up with Mary Richards (as he clearly did; see earlier post). No site that I’ve tried has the necessary evidence.

Have you tried the resources of the Dyfed Family History Society? I am a member, but I have only bought the microfilms relevant to my mother’s family.