Good Mornng
Not doing very well on this one.
I can find Ann Harry's bapt 13.5.1766 d of William Edward Harry and his wife Mary.
William Edward Harry was buried 21.2.1766
Older brother Thomas 9.1.1763
Frankly given the gaps in the records ,they could have had another 10 children and the Vicar wouldn't have noticed.
William Edward Harry is witness 10.4.1765 to the wedding of Evan Evans and Mary Lewis.
The Harrys seem to be the local family and the Daveys from elsewhere as you said.
There is a Lewis William David and his wife Elizabeth with children in the parish
Mary 13.3.1761,Elizabeth 2.2.1763 and Ann 20.4.1766.
He married Elizabeth Watkin at her parish of Whitchurch 15.5.1760
Lewis was buried 2.4.1798
It's possible that they were Samuel's parents, but I'm not saying that with any confidence.Given Samuel and Ann's second son was a John Davey I'd be looking for a father John.
Ciderdrinker