Two consignment vendors during stock determination

Hi all.

Under customizing related to stock determination I included to have prirority own stock over consignment (for both MM and WM).

My question is how is the stock determination performed in consigment when there is stock of two different vendors for the same part?

I read in Help-SAP that stock determination is applied first in MM and then the system forwards this data to WM (WM stock determination int his case is not possible). There is no sort for prices, nor quantity.

In my particular case, I have two steps for production process (REM); in this case no own stocks exists but consingment for two vendors:

1. In MF60 (movment 319) TRs are created (and then TOs) to move materials into 100 storage type. When 2 different vendors are managed I thought that the system would transfer the older quant but when both stocks are in the same storage bin with the same GR date I don´t understand exactly the stock determination made.

2. MFBF is performed to consume all components (movement 261K); here stock determination is executed again first in MM but I don´t know exactly how the system chooses the vendor

Could it be the criteria different in the first step rather than the second one, so I move physically stock from one vendor but informatically consumed the other one? is there a way to avoid this?

Any clarification will be wellcomed!!!