Clarification on reverse implementation of S4HANA from R4 to R2

Dear Experts, kindly usher connected a lawsuit merger concern wherein some are connected SAP HANA. However, owed to merger they request to bring 1 of the mentation down from R4 to R2 truthful that they person 1 accordant platform. Please counsel however to determination forward?

Please counsel if you person encountered akin situation, and tin stock the attack /guidelines/tools/techniques to grip the lawsuit merger situation.

Thanks successful advance, look guardant to proceeding back.