Special Stock Partner determination in Consignment

Hi All,

My requirement:

Special stock partner can be added to certain line items of Sales order this will be decide by article to be delivered to customer.

I created new partner procedure and made SB as mandatory and assigned to new item category. But it is not enforcing as mandatory when creating sale order. But when I entered manually SB and if I try to delete then it is enforcing as mandatory.

If I want special stock partner only mandatory based on Item category, how can we achieve this?

Could you please help on this?

Thanks,

Kiran.