Implications of Changing a Component on Existing Item Group/Kit

We realized we have been using an Item Group on transactions where components are:

Inventory Item 1

Inventory Item 2

Inventory Item 3

When really it should have been:

Non-inventory Item 1

Inventory Item 2

Inventory Item 3

This is an issue because the "inventory item" that should have been non-inventory is causing orders to be back-ordered because we don't have enough of that item in stock. In Sandbox, I updated the item to the non-inventory version, edited the Sales Order, had to remove the item group and then add it back in order for it to show committed.

I wanted to ask this group what the implications are of changing components from inventory to non-inventory like this on existing transactions? Do old transactions update to that non-inventory item ( we don't want them to)? Would it be better to create a new item group/kit with the updated components and apply that new item group to the Sales Orders instead?