I'm not sure if I understand the origin of the "Polly's Love" variant found in Aberdeen as well as County Dublin. Joe Éinniú called it, The Dublin Murder Ballad (also "Miss Brown" "Murder of Mary Brown" etc.), and he sang just one stanza:
In Dublin's fair city, in Dublin's fair town There dwelt a pretty maiden, her name was Mary Brown She courted a sailor for seven long years And at the beginning he called her his dear.
If anyone has information about versions and how or when it became attached to the broadside "Can't you love who you please" (usually just the last stanza0 please let me know.