How to specify the Order in which the system will pick release from the Sub inventories if none is specified in the release sales order form
Each Subinventory in the system can be given value for an attribute called "Picking Order".
This can be assigned as follows:
INV Responsibility > Setup > Organizations > Sub inventories.
In the Sub inventories definition form provide values to this attribute "Picking Order" for the sub inventories M1, M2 etc as 1, 2, ......and so on.
The lower the number of the "Picking Order" the higher is the sub inventory in the Picking Order for performing pick release.
Mention 1,2 in the picking order i.e M1-->1,M2--->2