A method pertaining to braking of a vehicle combination (100) which combination comprises a tractor vehicle (110) with a towed vehicle (112), where both are configured to be braked. The tractor vehicle (110) is provided with a first control unit (200) having a function for regulation of coupling force between the tractor vehicle (110) and the towed vehicle (112). Regulation of coupling force includes adaptation data and the towed vehicle bears an ID specification. The method includes the steps of: transferring the ID specification from the towed vehicle (112) to the tractor vehicle (110); during a braking process, registering adaptation data associated with the braking process together with the ID specification. Also a computer program product includes program code (P) for a computer (200; 205) for implementing the method. Also a system pertaining to braking of a vehicle combination (100) and to a vehicle combination (100) is equipped with the system.