How to automate light B comes on when light A automation turns other things off?

I'm sure I'm missing something obvious, but...
Using the "New" Room lighting app. I have an automation set to turn various things in one room on when one item is turned on, and then turn those things off when that item is turned off.

What app and/or sequence would I use to have the "turn off" automation trigger a turn on lights automation in another room? I initially thought it could be part of the same automation but it appears there is no way to have the turn off trigger also trigger turning on other things.

Under "Means to Activate", you can select to have it activate when a switch turns off. So, you would go to the instance for room B and add the device from room A being turned off as a "means to activate".

But in the dropdown under "Means to Activate Lights" there is only an option for "Switch turns On" There is no "Switch turns Off" option...

I also tried, in Means to Activate, "Custom Attribute", selecting the device, attribute = switch and value = off, but that does not work because HE thinks room B should be on anytime room A is off. I want room B light to automatically go on ONLY when someone taps the room A switch to activate room A off sequence...