One Identity Manager 8.1.5 Set Account Disabled on UNSAccountB when Fully Managed

We have a custom target system that we sync to that has a account disabled property that is synced outside of OneIM using the OneIM API and the targets API. The only issue is setting account disabled on the UNSAccountB as the object is fully managed but for this property, the target is the authority. The Account Disabled property appears to be governed by the status of the attached person record. The only way I found to be able to change it is to remove the "overwrites" value of the field definition - but I don't want to do that. How else can I make it so I can set/change the account disabled property of a UNSAccountB object that is fully managed (as the target system is the authority in this case)? Is my only option to make it -not- fully managed? If I make it not fully managed, will the custom target system still call all the UNS scripts when adding/removing/updating the accounts?