Are the credit cards in arrears or anything? If not, there'll be no problem. Similarly, is there any problem with her just changing the address on the accounts?
If things start to go wrong with her bill paying and she doesn't change the address on the credit cards I'd either write "return to sender" on the bills and put them back in the post box or if she gets into debt, contact equifax or experian (or both) and notify them that you have no financial relationship to her (if you don't, that is). "Notice of dissociation" is the jargon.