Hello Android,
Yes, indeed we are souring consignment stock and a Business rule forbids us to mix the stock in the same bin. I think the background is that suppliers must be able to phyiscally check the content of their bin in the warehouse.
To answer your other questions:
- Yes, we do allow mixed stock as long as we do not mix suppliers on consignment basis
- We have a few rare cases of SU management, but nor for materials source via consignment
- Yes, we do make use of Batch Management
In fact, I was thinking about some kind of error message that is being display in LT01 (and LT10) once the "wrong" bins have been chosen.
Thanks a lot 
. Cheers
K.