In Family Page (maybe fam news page) add a “ticker” that pops up every planet lost to another family and have it show many ticks it has been missing. Allow the leader (maybe vice leaders) to remove a specific planet or it comes off when the planet is back in family control
example:
56,32:1 - Ticks 2
58,48:9 - Ticks 8
60,12:3 - Ticks 22
Make the planet linked to click on