as my grandfather once told me, "i am your grandfather"
if she didn't know
Isn't this instrumental, rather than accusative?
"Jesteś moją trzecią córką" is instrumental. An example of accusative: "Widzę moją trzecią córkę" = "I see my third daughter". See https://en.wiktionary.org/wiki/c%C3%B3rka.
That's what I thought. The hover translations of the adjectives indicate that they are in the accusative. The form is the same, of course, but it had me momentarily asking myself whether Poles used the accusative after a copula.