GOP - Is there a way to design GOP setups so that any ordered item gets sourced across business unit

Looking out for recommendation to enable the GOP setups to handle below business case scenario:

1) If an order is placed for BU1, the item should be first sourced from inventory orgs within BU1 based on the ranks in the sourcing rule

2) But, if on-hand is not found in any of those inventory orgs for BU1 - GOP should look out for supply in inventory orgs in BU2

*This needs to vice-versa as well - So, if the order is placed for BU2 - the supply should be first looked in inventory orgs of BU2 and if no onhand exists then GOP should look for supply in inventory org for BU1