Every brother has his own family, but the elder brother always asks the younger brother for help. How could he refuse?

It depends on how your brothers feel. After all, parents only have two brothers, so it is good for them to help each other, and your children may get help from their brothers in the future, which can set an example. If you ask one party to pay the bill blindly, this fraternity is unkind. You can politely refuse and find some reasons. It's not good for you to be a brother without tearing your face.