Hi,
Alternatively you can think for a concept with development by linking purchasing group with storage location in ZTABLE or linking cost center with storage location in a ZTABLE1 where you can enter your purchasing group in cost center(KS01/KS02), so post these materials into single storage location but you can not stop posting to other storage locations in standard transaction codes .
Final thought- you can go for new plant creation and then keep your that storage location under new plant. Now you can restrict your material type for this new plant in OMS2 with quantity and value update by allowing only for new plant. In this case you can create all materials with new plant and storage location where in standard system restrict to post these material to other plants and storage locations, and allows to post only to new plant for that storage location.
Regards,
Biju K