Reuben Isaac Edwards - Name

Is there any better documentation for this person's name?

Asking because he's supposedly my son's paternal ancestor, so I'm trying to be sure I have the details correct. His tombstone doesn't use the name Reuben - just Isaac.

And his Find-a-Grave page only lists one wife, not four:

https://www.findagrave.com/memorial/29182848/isaac-edwards

So, I'm not certain about the connections or whether he's actually my son's direct ancestor as indicated on Ancestry. My son is from a Mary 'Polly' Edwards who married Josiah Ellington. Some sources have this Isaac Edwards and his wife Rachel Miller as her parents.

Mary Ellington

She isn't attached to her mother at the above profile but is attached to this Rueben Isaac Edwards as his daughter.

Same on her Find-a-Grave page, just lists her father:

https://www.findagrave.com/memorial/84967990/mary-ellington

Ancestry shows:

Mary Polly Edwards

sources (9)records (8)photos (1)
Family Info

Father
Isaac Edwards (1775–1845) - again, no first name Reuben attached to the father

Mother
Rachel Miller (1780–1835)

Spouse
Josiah Ellington (1785–1845)

Thanks in advance for any additional info / assistance with the connections.