I have only gleaned this info from other trees but none show search results.
Do records exist from this era.
If there are no records, then the info on the trees in question must be guesswork only.
If they don't show sources, then the info may be guesswork anyway, even if there are records! I wouldn't take what you see on online trees as valid information unless you can back it up from original sources. Take it as a starting point of where to look, or as a suggestion, but never as fact!
Have you checked SEAX to see what the earliest PR's for the relevant parishes are?