Client Merge..

Experts.. Need yor advice..

we have a requirement where in one of the client 555 is on ECC IS-Mills and the other client is 999 on ECC w/o IS-Mills. Can client 555 be merged onto client 999 or 999 be merged on to 555 so that one of the client can be eliminated?

Can someone pls advise on feasibility and technical steps?

Same is the requirement of one IS-Retail and other ECC.

No enhancement pack in any case..

THanks for your advice