I am wondering if the function ‘AddDynamic’ is still in use in 4.12.
The compiler keeps saying it’s wrong.

The function signature has been changed in 4.12. You can see it in the patch notes / the API.

This is the new signature:

(UPrimitiveComponent* OverlappedComp, AActor* OtherActor, UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult)