I think the best verification now will be Ann's marriage and/or death cert to confirm her parents' names. Possibility that she might have been illegitimate (just a guess on my part!), but at least, with confirmation of mother's name you should be able to firm things up at least on Ann's maternal side.
Some bits for you to consider. I think this might be Innes in 1841 (names all connect with her later life!):
Ann Berrie 37, pauper
Arthur Berrie 7
Innes Berrie 6
Address: Cairnrorie, Leochel-Cushnie
So, Ann (Henderson) likely called after her mother and Innes' first born son with John Posser, called after her brother Arthur?
One possibility with the names that Norma found from 1861, the Dewars, as grandparents to Ann Henderson, is that Ann Berry, grandmother to Ann Henderson, went on to marry a William Dewar perhaps?
From 1861:
Williams Dewar 65, sawmiller b. Cleny (Cluny?) Aberdeenshire
Ann Dewar 55 b. Leochel Cushnie
Ann Henderson 7 granddaughter b. Leochel Cushnie
Address: Millnewks (?spl) Leochel Cushnie