Perhaps you can explain iBird Pro’s family sharing. I have it installed on 3 machines: my iPhone, my iPad, my wife’s iPhone and her iPad. The app works on all 4 but the in-app purchases only work on my iPhone. Restore purchases doesn’t work on any of the other units.
I purchased the apps on my iPad (after I had purchased them on my iPhone) and they now work there. I tried to purchase them on my wife’s iPhone and was told to purchase the app (iBird Pro) first. I uninstalled and reinstalled the app with no change
Obviously, I’m not pleased to have to make additional in-app purchases.