I am a musician, and often play for weddings. There are often times when the wedding may not be valid; for example, if they've divorced and are getting remarried, the minister is female, one person is a fallen-away Catholic, etc. I obviously can't interrogate the couple before agreeing to play for their wedding, so I usually can't tell whether the ceremony will be valid or not until I get there.
Should I play for weddings that I'm not 100% sure about, and hope that there isn't a problem? Or should I only play for weddings that I know will be valid?