Creating a material BOM with CS01 Tcode

Dear Friends

I have a question on using copy function for creating a material BOM with CS01 Tcode. Here is a situation.

I have created a group BOM for a product P1 which is using components C1, C2, C3 and C4. Now I am creating a BOM for P1 in a plant 0001 by copying a group BOM. In this case system lets me copy a group BOM and allows me to edit components after initial copy. This will create BOM with alternate 1. After that while trying to create alternate 2 for the same product P1 in plant 0001 by copying a group BOM system does not let me choose a group BOM to copy from. It always proposes alternate1 to copy from. Is there any way in ECC I can copy a group to create another alternate? We are on SAP ECC 6.0 version.

Any insight is highly appreciated.

Thanks.

Sharath