Using Assembly or Sales BOM Item in Purchase Orders

Hi,

I have used "Assembly" and "Sales" types of BOM to represent kitting of items in Sales Orders. First, I defined a "Kit" item as "Sales" type of item in Item Master. Then I created a "Assembly" type of BOM for the "Kit" item. The child level items in the BOM are inventory type of items. Then I could use the "Kit" item in the sales order.

However, when I try the same method to create a "Assembly" BOM for a "Purchased" type of item, I receive an error message "Only a Production BOM can be defined as a Purchase Item". Is there any way to define a "Assembly" type of BOM for purchasing item and use it in purchase orders (to represent kitting)?