I'm working on an old script I started about 5 years ago. I've sent it to a friend to collaborate on and I'm quite optimistic.
It looks really great but the only trouble is there are a few lines that look too funny for me. I sent it to a couple of people to see about collaborating at the time but nothing came of it. However they added these lines.
It only totals three or four lines at most. I don't though have contact details for either of them and I don't know who exactly wrote what.
So what do I do? Give them a credit and as a result lose a percentage of any possible fees I may get or just put "Additional material by..." OR just keep quiet and hope they don't notice.