FMS: Please help with BAPI/iDoc to create Variant for existent Generic Article

We need to create a variant for existent Generic Article using BAPI?iDoc.

Here is how creation of a variant looks like when you use MM42:

Press on Variants button:

Check Color/Size desired:

Go back to the main screen and safe.

Do you have a sample code or suggestions how to execute same update using BAPI/iDoc?

I was trying to use BAPI_MATERIAL_MAINTAINDATA_RT, populating structures VARIANTSKEYS and

CHARACTERISTICVALUE and I can’t get any result.

Your help would be greatly appreciated and rewarded with points..