[Mmartin]

You can use various methods there. Either disable the checkpoint as soon as anyone enters and re-enable it after he finishes the operation in it, or let the checkpoint be and create a boolean variable for CP's availability - setting and checking that instead of disabling and re-drawing the checkpoint. You can also look through all players and check if anyone else is in the checkpoint and then either do or not do the operation - but I'd not recommend this one. Pick the 1st or 2nd, nothing hard to script.

Also, find a spare time to read this: https://sampforum.blast.hk/showthread.php?tid=395711