The main catch in this puzzle is identifying that R1 and R2 share the same Y value.
Once that is known, you have enough information to solve for the private keys.
I think only a dozen people in the whole world can understand this math Once that is known, you have enough information to solve for the private keys.
I will try to follow the calculations, but it will take a lot of time for my old and sand brains.
Anyway, thank you a lot for this.