I have never done this, but I also do not think that there is any reason for TA to check the name of the credit card owner to the passenger. I occasionally purchase airline tickets on other airlines for my children using my own credit card, and there has never been a problem. I cannot imagine why they would care who pays for the tickets so long as they are paid.

I would not be worried about it. If your family members have their reservation number and flight times I do not think there is anything else you need to do.