Music collaboration copyright

Hello,
I'm working on a musical collaboration, of which there are two parts: the music itself written by the composer and the text written by me. The text is based on a book that I have written (about 90% identical wording). We are drafting a partnership agreement and it currently states the following: "All property of the partnership shall be jointly held in the name of the partners individually". Does this mean the composer is the sole copyright holder to the music and I am the sole copyright holder to the text? If not, how can I amend this wording to ensure separate copyrights?
Thank you!