sorry that went "post" unexpectedly!! The trouble with songs one has written is that we remeber the Drafts too, and easily can get sidelined or lost in earlier versions and dead ends!! so it takes a long time to get a "definitve " version in MY head!!
on the main issue.
Out of politeness,If I am in a song circle waiting to be caled, I try to have a couple of alternatives prepared so that if someone sings a song I had in mind to do I can switch to an alternative, I only feel irritated by "song ownership" when it is used as a excluding tactic by individuals or groups against newcomers, but on the otherhand it encourages songwriters to do their own songs(it certainly encourages me) so that they are fairly sure they are not stealing someones thunder!!