Hmm well after double checking you might be fine even without the banner. But everything will think the banner is on its previous location (shops, etc).
You can spawn one but it won't be taken into account.
Let us know if you get any errors that look caused by the banner not being there.
I'm going to add this to our bug list. I remember when removing a building with hearthlings inside would also destroy the hearthlings. Such horrible bug