There are public trees which show Doreen Margaret Callahan.
They show that she married Vernon Craighead Davis.
One has parents Walter and Alice Maude but no records.
2 others have mother Margaret O’Callaghan but no supporting records.
Might there be Australian records showing Margaret and Doreen together?
I don’t have access to US records - just bare minimum but there seems to be a Margaret A Callahan birth and baptism. There is a tree indicating that she is Margaret Alice and parents are shown.
However, I searched for 1911 but I can’t see any date to check but there may be other birth entries around 1911 in the general area.