Emergency shutdown of batteries and inverter without disconnecting from grid

I'm planning an installation based on a gridboss, flexboss21, and 2 indoor wallmount batteries, installed in my garage in California. 

I'm planning to install a heat alarm above the batteries as required by code, and I saw someone's idea that it could be connected to the rapid shutdown switch, which seems like a good idea to me. But as I understand it, the rapid shutdown on the gridboss will open all the relays, cutting my home off from grid power entirely. That sounds good for a manual activation by a firefighter if my house is actually on fire, but I'm hesitant to make that automatic when the heat alarm goes off. 

Is there a way I can connect the heat alarm to just trigger shutdown of the inverter/batteries, without opening the MID relay in the GridBoss? Maybe if I just wire it to the RSD port in the FlexBoss21, but not to the one in the GridBoss?