Production Planning Raw Material Warehouse Selection

Hi, I am trying to make a production plan.

Let’s say I need 10 x item_a. WarehouseA has 5 waiting qty because of an approved purchase order or material request. If I select WarehouseA as Raw Materials Warehouse. Planning will consider this wating qty as I have the items and reduces purchase request by 5. Finally tells me to create a MR with 5 item_a as puchase.

But if I select WarehouseB as Raw Materials Warehouse and select Transfer From Warehouses as WarehouseA it does not consider that 5 items as incoming and tells me to create a MR with 10 item_a as purchase.

Do I need to make code changes or am I doing something wrong ? What should I change?

I always need the items to go WarehouseB first. Then I will transfer them to WarehouseA as they arrive but with this setup I am planning wrong and buying too much items.

Any suggestions would be appriciated.