Segregation of Stock

Looking for options on how to manage segregation of finished goods sku's that have been manufactured based on a forecast. The sku has a forecast of 5,000 per week.
2500 to be consumed against a sales channel
1500 by another sales channel
1000 by another sales channel

We need to segregate the stock for each of the quantities fort he same sku and the customer sales channel should only be able to pick against the segregated stock.

Can we use sub inventories with WMS rules manging the put away and picking rules or doe we need to use multi inventory warehouses.

How would we build out the rules to identify how much of the sku should be stored in each sub inventory?