There is no restriction on opening a bank account whilst bankrupt. There is a restriction on obtaining credit. So the thing to do when opening a bank account is to decline overdraft facilities. PermanentTSB and EBS are the best bets, because they expect you to operate the account in credit. Your sister should just walk in and say that she is interested in a current account that has no charges. Let the bank official then take her through the steps. She is not obliged to volunteer that she is bankrupt, because she isn't applying for credit. However, if she is asked, "Are you bankrupt?", either verbally or on an application form, she would be best advised to answer truthfully and hope for the best.
If she brings her passport and two forms of address, including a utility bill, she might even get her new account there and then. Also, if the new bank offers to carry over direct debits/standing orders your sister should decline this offer. She doesn't want the new bank talking to the old bank.