I thought that was exactly what that picture did?
Though a picture speaks 1000 words, I'll try again in words, mainly copying from the first post:
I have FX, iPhone, iPad.
iPad connects to FX by WiFi, running SkyDemon, using Pilotaware as its source.
iPhone runs SafeSky and SkyDemon, set to GDL90. It only uses mobile data.
The two iDevices are mutually entirely independent.
However, the FX connects to the iPhone for iGrid using the iPhone hotspot.
Unless you tell me differently, I do not believe that the FX using the iPhone as a hotspot would introduce SafeSky in any way to FX.
However, I am making four flights on Saturday, and I will simply run the iPhone as a source of mobile data for iGrid and nothing else, and see whether the problem persists. I am convinced it will.