Source an Inventory Item from Another Inventory

While we do not have a centralized distribution, we do have one Store Room that is significantly larger than or other four. For this purpose we've reduced our On Hands in the smaller store rooms and are fulfilling the On Hands for those reduced items from the larger store room.

I understand that we can set the whole store room to source from the larger store room, but we're more interested on only sourcing specific items from the larger store room... the other items would still source for their respective suppliers.