First, who said anything about tacking anything onto Dougie's song?
Second, if I do a song in church (or anywhere), I always credit the songwriter(s) if I have that info.
Third, I wasn't aware that people were usually expected to pay royalties for a live performance of a song in a non-commercial setting. (Are we expected to pay royalties every time we sing a non-PD song at a singaround or song circle or around a campfire?)
If that is expected, millions of singers/musicians are flouting the law and cheating composers and songwriters out of their royalties every day.
(Printing sheet music for a song for use as a choir anthem is a bit different. Choir directors routinely do pay for that sort of use.)