Anyway way to set an interface IP not reassigned during netif ?

Im' using the machine as a gateway and use one of the interface as an OOB access to the applications. I should be able to launch automated commands to re-configure the applications an other network interfaces from this OOB interface. 

The issue I have is that when I update the rc.conf and launch the command `service netif restart` and same for the `routing` it will reset all interfaces and reassign the configuration to them. Which disconnect the client making the upgrade. What would be the way the way to prevent it? 

For now I'm thinking to set the interfaces and routing  separatly but hen I miss the flexibility of rc.conf . Is there another way to do it and ensure an interface won't be resetted?

Benoît