COPA planning alternative of measurement in Accounting based COPA

Dear Experts.

Client implementing S/4 HANA with simple fiance. AS SAP recommended using ACCOUNTING BASED COPA.

The requirement is as below-

Client selling materials with base unit of measurement is CARTON but needs COPA report CARTON and KG wise. To meet this requirement using BADI, Actual data is coming correctly in COPA report. CARTON and KG(This is additional quantity field 1).

Now the problem with Planning he wants to do planning for both unit if measurement. In KEPM layout i am not able to add Additional quantity field 1 filed(System giving error message).

Please suggest how can do COPA planning in both UOM in KEPM?

Note- Using ACCOUNTING BASED COPA

Thanks,

Chandrasekhar