Communication difficulties

This is nothing I normally have, but listen to this. I'm off to this party on Friday. It's a combo-celebration. My friendgirl is celebrating her birthday. Her Mum is getting married today I believe, and is celebrating on Friday too. The guy she's getting married to is friendgirls boss, and whaddayaknow, he's celebrating too on Friday. First I had trouble with presents, since I only met friendgirls Mum twice and her husband not at all. Finally I settled on the same for friendgirl and her Mum (will be revealed later, since I cannot be sure friendgirl peaks here), but what to buy for the guy? Think I will bring a good bottle of wine. That's impersonal and usually appreciated. Gosh, think if he's a non-drinker? Nah, cannot be. All good and fine so far. Now comes the cards. Do I write a personal card for all three? Or one to friendgirl and one to the supposedly happy couple? If so, what do I write? Happy marriage? First of all, is there such a thing? Good luck? Nah, that sounds like they need it. Gaaah! This is difficult. Besides the Mum doesn't speak English. Does that mean I have to write it in German? Njet. I'm gonna presume the guy speaks English. After all, he was the one who read my blog with friendgirl in the mornings, remember? Think what I'll do is to write one card for friendgirl with a greeting to her Mum and the guy on the same card. Then put friendgirls + Mums name on another envelope, containing the gifts + hand the bottle to the guy. Will that work? What is customary? HELP!