How can I design a registration form with 10 fields for multiple users?

I'm in a situation to design registration form that asks A Dad [a user] to register his "Son or Sons" in a sports activity and pay for this registration.

In order to enable Dads to pay one time even if they have more than one son to register - 2 or 3 sons, for example,- Dad should add all details for every son individual. Usually, this details is about 10 fields, they are all required and there is no way to reduce these fields or details.

How can I ask Dad [a user] to add every son details individual in a simple elegant way that can be applied in web and responsive for mobile user interface (UI), in other words, I'm looking for best practices UI Patterns for inspiration in such a case.

There is no problem if a dad has one son because in this case, he will add the 10 fields details one time.