DNA by itself is unlikely to 'prove' your latest DNA discovery, Jill. It still needs careful research to back it up fully. But part of that careful research can include circumstantial evidence of likely places and people, as well as the DNA evidence.
After all, if you go back in your tree before census and civil registration began, your evidence is nearly always circumstantial. Mary Smith was born c 1820 in X, Kent and is living with her parents, John (a baker) and Mary Smith. Look at parish registers for X, Kent - a Mary Smith was baptised there in Sep 1819, parents John (a baker) and Mary Smith.
John Smith married Mary Brown in Y, Kent in Mar 1819.
Is this your Mary, or another Mary? Is this her parent's marriage, or is it of another couple?
In this case, with the common surnames, it is just as likely to be incorrect - with more unusual names you can be more certain. But was Mary pregnant by another man before they married?
DNA can help you 'prove' whether it is correct or not. It is another tool to help verify your paper trail, not something which can be used independently. As I said before, enter him provisionally (which you have done!) and research him backwards, forwards and sidewards, see in the coming years whether other DNA matches strengthen or weaken the connectIon.
And document your uncertainties, if you have a public tree someone is bound to copy it as fact!
Regards Margaret