If you have several bears, the moment they are sealed and turned into Tombstones where does the Church pop up?

The church appears where the most recently-placed bear is.

So how do you keep track of that, if you have 8 bears all moving around and you bury them with some grass or a bush?

For Facebook version at least, the most recent bear was slightly darker than the others. That does of course create problems if you split the pack into two, but you should be able to at least identify one of the places a church pops up. Unsure if the same is true for the desktop version though.

JMich is correct.