Cant see a Henry and Sarah on any census with Elizabeth - so personally I would want to know where the compilers of the trees got that info from - e.g the christening details.
Anyway, I was thinking about this thread, and go back to one of my initial questions - have you got a child's birth cert confirming that their mum's maiden name was Banyard?
If not, one explanation of the situation could be that Mrs Elizabeth Addison was not nee Banyard at all, and the marriage cert with dad Charles relates to another couple altogether, a Henry and Elizabeth Anderson, as per cert.
Thus 'your' Elizabeth, born 1842ish in Dowham is ELizabeth something else.
I know there is not an obvious marriage for Henry Addison to an Elizabeth (other than Anderson to Banyard) but maybe they didnt actually marry, or something.
Agatha. if you havent got a child's birth cert, I think, in my humble opinion, that is the way forward, to get some sort of confirmation that the Banyard track is the right one, seeing as nothing on it makes sense!