Possibly some interesting connections here:-
There is William David John(?) as son in law to John Jones(1705 will)
I think he is synonymous with William David/William Jones of Meiarth,Gwyddelwern,as there are wills at NLW fiked under both names dated 1715
Other wills for this property yield a similar duality in the name of John Salisbury/John Wynne dated 1676.There are later wills for the Wynnes here also Robert(1726),John(1755),Robert(1758)
On the "dating old Welsh houses" site there is a Llandrillo entry for a Maes Tyddyn,also believed to be Ty'n y Maes.
In 1716(the year after William David's death there is an indenture from Samuel Parry of Plas Vaerdre to Robert David for the sale of Ty'n y Maes
There is then an MI for Robert David in 1758,aged 91(1667-1758?) and a wife Catherine in 1759 aged 94((1665-1759)
There is a will for Robert David,Gent,Ty'n y Maes,1758
This later data together with a later quotation of 1789 "...Robert Lloyd,late of Ty'n y Maes,now Ty Ucha..."I can't quite tell from the (lack of)context whether the property is synonymous or whether Robert Lloyd lived at two different addresses.
So there is William David/William Jones and Robert David(could he also be "also Jones?) and then there was that John David......
Regards
Roger