How to gently remind relatives to pay back the money?

First of all, your psychology should be changed to (I don't need any reason to ask you to pay back the money, as the saying goes, borrow money to see feelings, pay back money to see character, and let me witness character). With this mentality, you can come straight to the point and say directly (hello, I am short of money recently, and if I still can't turn around, you can pay me back in batches every month, which will reduce the burden), that is, you don't have to ask the other party if they have any money.