How do I move an off-screen family instance only if there are no instances of that family on screen?

After many years this still seems to stump me: I have some instances of a family outside the visible screen area. Every x seconds I want to take one of them and move them to the the visible area, but only if there are no instances of that family already on-screen. In other words, only one instance of that family should exist at the same time on the screen.

I tend to go for the "is on-screen" condition, but then my subevents wont fire if that condition is false.

Is there a simple way to do this or do I need to start adding variables to keep track of the amount of family instances on-screen?

If you add an Else it will run the events you want when there is no instance on screen

That indeed does it! :)

Thanks for your help!