Concerning Collaborations and Copyright
As it relates to collaborations, having produced a drum arrangement or bass line for your song, if it used for personal practice or demonstration purposes, then there is no formal agreement on the production.
If the production is released then I would request the honorific usually applied to collaboration in the form of production credit for the portion of the collaboration.
Should the collaboration involve content in the form of musical input, like lyrics or song arrangement in so much as it changes the song significantly, then an appropriate share of song-writing credit will be afforded me.
Barring all of the concerns, your original material belongs to you, and no attempt would ever be made by me to represent it as mine, no unauthorised copies will be kept, nor would any claims over copyright be made for material that was not produced by me.