If a mother and her son attend a wedding together, but they don't live together, is it appropriate for each of them to bring their own gift?

I was wondering because my mother, her live-in boyfriend and I attended a wedding together. Both my mother and I gave the bride a card with a check for $100 enclosed, but only my mom got a "thank you" card in return. This upset me, especially because my mom's boyfriend lives off of her. She works... show more I was wondering because my mother, her live-in boyfriend and I attended a wedding together. Both my mother and I gave the bride a card with a check for $100 enclosed, but only my mom got a "thank you" card in return. This upset me, especially because my mom's boyfriend lives off of her. She works while he stays home, and she's embarrassed by him and therefore makes up stories about what he does for a living. So I was not quite fond of the fact that her boyfriend received credit for a gift he obviously contributed nothing to. Yes, I know that "thank you" cards are not just for the gifts, but also for attending the event. But the fact that I bust my behind from 9 to 5 to afford to give the bride a $100 and get no thank you in return, was quite offensive. FYI, mother and I live just a 15-minute drive away, thus how easy it was for us to go to the wedding together. For that matter, was it tacky of me to bring my own gift? I mean, should my mother have put my name on the card, too? I don't know what I did wrong here, and I have the funny feeling that the bride perhaps despises me or something.
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