How many original songs should our amateur band include in a party set?

Our guitarist put four of his own songs into the thirty-minute set list. The party organiser had asked for familiar tunes people could dance to. I pointed to that message, and he said, 'Nobody will discover our songs if we never play them.'

Three of us have been rehearsing for this friend's birthday party. We're doing it for fun, not as a paid booking. We've learnt several covers and worked on his originals too. I like two of the originals, but they aren't songs the guests already know.

I suggested one original between familiar numbers. He said that reduced his writing to a token slot. Our drummer doesn't want a disagreement and has left us to settle it, though she'll have to rehearse whatever we choose.

How do we give the band's own work a place while respecting the evening the organiser asked for? I don't want to claim in advance that guests will either love or dislike songs they've never heard.