Can a stock free goods item be given on an order price adjustment?

Hi,

I have a question regarding advanced pricing and free goods.

I need to create and adjustment for the following sales order scenario:

If a client buys in the same order 1 unit of item A + 1 unit of item B, then 1 free unit of item C should be created for free.

I was thinking of creating an order adjustment, but it seems it only works for non stock free goods, and item C is a stock item.

Is there any way to set this adjustment?

I discarded kits funcionality because items A and B are independent, and one of them can be cancelled later on in the process.