Unable to Assign Inventory Org to Cost Organization in Mange Cost Organization Relationship

Summary:

Due to change in COA our legal entity was modified. Due to this the Cost Organizations that we setup had to be inactivated

Now when we have created new Cost Organization. When we try to assign Inventory Org (old) to the new Cost Organization under manage Cost Organization relationship, the inventory org is not showing up.

Is there any way we can delete the Inventory org assignment from the previous Cost Org Assignment. The system is not allowing me

Is there any way we can assign the old Inventory Org to the new Cost Org? If not then is there any workaround? The last resort would be to perform the Inventory setups again and then assign, but we want to explore all possible options before we take the option for the last resort.