PO Release Strategy

Dear Experts,

I want a solution for a problem REGARDING PO releasing. The release strategy for releasing a PO is at three different hierarchal levels i.e A , B , C firstly PO is released by A and then by B and then by C and (untill the PO is released by the previous level it is not visible for the next hierarchical level) and thus the PO is released completely but while un releasing the same ,the reverse order is not automatically followed that is firstly C should unrealease and then B and after that A rather A directly unreleases the PO and thus all other automatically gets unreleased and A makes the changes . Now this need to be changed that untill C unreleases the Po, The Po should not be available for unreleasing to the lower levels as it is in case while releasing.

thanks,

Rahul Vaid