I had this so there is 2 options.
A. change it to group 2 so they both have to leave to trigger but only one has to arrive (this works great for me as it was the arrival that was my issue)
B. Turn on a delay for leaving also in his app. This would stop the in outs asking as it only disappears for a while (again this is like mine, but I'm Andoid)
Edit if you do go with A delete the old child app and start again on each presence device. Then make sure you toggle all the inputs so the app knows the state of the devices. Since I have done this @Cobra presence central app has not dropped a beat.