Capt. Mooron wrote:
Canada allows dual citizenship...... maybe it's just a matter of her
not
renouncing her Canadian citizen status.

As far as the US is concerned, she did renounce it, because the US
naturalization oath has a statement of renunciation. BUT, that
statement has no affect under Canadian law, and Canadian law determines
who is and who isn't a Canadian citizen. So, while she must deal with
the US as a US citizen, she can continue to deal with Canada as a
Canadian because Canada says that she is a Canadian.

Stephen Gallagher