How can I prevent product reassignment by other fulfillment apps?

[gvbrown]

We run a fulfillment app which, in some cases, has products that implement sku sharing.  Great feature is some cases, in other cases, it can be a nightmare to deal with.  

Here's what we are dealing with currently.  

We have a product that is only fulfilled in one location (ours). 

There are other fulfillment apps running on the same store.  

Occasionally, another application will connect or assume the fulfillment role for one of our products.  Orders then get reassigned to the alternate location, which creates orders that have to be reassigned, or even worse, split fulfillment orders in the case of multiple item orders. 

Ideally, we would love to disable the sku sharing feature for certain shops to prevent this behavior.  Shopify indicates that this is not an option, once it has been enabled. 

Without the ability to disable sku sharing - another possible option would be to "lock" a product to a specific location, or indicate that an individual product can not be shared. 

In short - how do we prevent specific products that should not be shared from being reassigned by other fulfillment apps?