HI Akshay,
I am not very clear on your issue But whatever i understood from the description, please find below my comments and let me know if it answers your query. first of all, In your case, I assume your plants are already defined with 4 characters only.
1) Either you do assignment as ORGANIC - MCB, ACID - DCB, AMINE - Utility & ALKEMY - ETP
2) OR you define one more planning plant in regular plant definition and assign it as planning plant to ORGANIC,ACID, AMINE , ALKEMY .
Regards,
Amol