You should always register songs based on the writer's share, and not the publishing as that's how societies accept registrations. So if you want to collect 100% of the publishing for a work you do not control 100% of the copyright for , you will need to register that writer as a client writer (rather than an outside writer) that way we can inform your PRO that your co-writer has given you the right to collect their publishing for them (while they still can get their writers share directly from the PRO). Lastly, please note that in order to collect the publishing share of royalties for your co-writers you will need to be able to provide proof of agreement as the writer would need to sign the LOD within your account.
Not sure what the difference is between a client and outside writer? Click here to find out!