بسم الله الرحمن الرحيم
(1) If your relative is poor i.e. he is entitled for wajib sadaqah then your parents may help him with the interest money saved in their account without the intention of reward. It is lawful and he may spend it in his entire needs where he wishes. And if he is not eligible for wajib sadaqah and your parents do not make him the owner of the interest money rather he takes it from your parents and pays off his interest from this money on behalf of your parents then it is also lawful.
(2) If there is no interest dealing in checkings account whereas it is found in current account, then you may open checkings account as per the norms of the bank. Then you should close your saving account and open checkings account.
Allah knows Best!
Darul Uloom Deoband