I think the simplest way to handle this is using a transparent image on scene B object as a “boolean” value.
Add an image object in scene B with a completely transparent PNG (or you could just use a transparent hotspot). Set it to initially not visible.
If any of the hotspots on scene B are selected, add an action to show the transparent image/hotspot (which won’t actually show anything)
For your condition on Scene A check to see if the transparent image/hotspot has been shown
I use logic similar to this for the Office Safety scenario.