So sorry that this was so ackward for you but you did nothing wrong. I don't know why people don't think to tell us these things. Several years ago my sister-in-laws new husband (that has 6 kids from teen to adult) brought one of his older daughters to our family meal. We always bought for his youngest two kids as they were the only ones we'd ever met and were at the family gatherings. We all felt very ackward because there were gifts for her younger brother and sister from us all, but neither her father nor my sister-in-law thought to give us a warning that she'd be there.