well legally if you kill the deer, you legally cannot have another person tag it, that's the law in most states
by shooting a deer with intentions of another tagging it also is WAY in the gray area
that said, I have been in your shoes a few times, and I help end the suffering, some times I even ate a buck tag due to the first shooter leaving??
and that sucks a lot more than loosing a doe tag, but its the right thing to do
I would have said something ebfor etracking, all the more so if I seen the kid wasn't taking [part in the tracking, that would have been a red flag to me right there LOl
but hey, some times doing the right thing is the reward, so be glad you did it, even if it cost you a tag, Karma, can go both ways on you and them, maybe next yr you will kill that bg one, and they will go deer less!