I don't think the Melody and Lyric are joined until the composer and author agree to join them.
Until then, or if one rejects the other, no contract exists.
A contract consists of an 'offer' and an 'acceptance'. The offeror does not have to 'accept' any 'acceptance'. They can reject the 'acceptance', as a 'counter-offer' to the original contract offer. (See why lawyers become necessary? I too am not a lawyer.)
I forget the information on this 'case' but if the original 'offer' to write a Lyric to a Melody, or a Melody to a Lyric, was responded to, but not 'accepted', no contractual obligation was made.
The Lyricist still owns their Lyric. The Melodist still owns their Melody. The two were never contractually joined as one composition.
All correspondence between two parties, the 'offeror' and the 'offeree', should be maintained. This is part of transitioning from hobbyist, writing/composing as an avocation, to being a company engaging in commerce with another company, or consumer. You have to get formal, like any company, creating files, documents, a paper trail that can be referred to should any legal conflict arise. Your lawyer will appreciate your diligence in keeping records, enabling her to argue your case. (Yes! Your lawyer is a woman and you'll fall in love, be married, have 11 children and then she'll sue for divorce, and keep the house, making her your House-Keeper.)

Last edited by Gary E. Andrews; 10/30/19 08:23 AM.
There will always be another song to be written. Someone will write it. Why not you? www.garyeandrews.com