iv had some experiance around this..
me and my woman use something called "virtual creditcards".
this gives us a new card number each time we pay online.

and sometimes we use her cards and sometimes we use my cards.

one of my accounts was suspended.
after a bit of jibber jabber in mail with blizzard i got it back and they made me unable to pay with creditcard on that account.
so now i use gamecards to pay that account. the rest.. i am still using mines and hers on and off on them.

so what can raise suspicion is using different names on the cards as to who owns the account and/or who has paid for it in the past.

doing as you are doing is no problem at all.