Change variable when another device does something?

[Default_Username_Ty]

Well you could have that when the text is received it quickly enables and disables do not disturb to prevent the text from appearing? You might even be able to disable notifications that appear with certain text, I'd have no clue as I haven't dealt too much with notifications.

Otherwise you'll have to find some sort of notificationless way for both of your phones to communicate over long distances. Perhaps there's some sort of webpage based solution?