I have something working but i'm not convinced.
So here is what i have done :
Door got variable Open=Number
- Condition : PlayerFamily on collision with Door
- Action : Door add 1 to Open
- Condition : For each PlayerFamily And PlayerFamily is not overlapping Door
- Action : Door set Open to 0
Result : If all Players are on the Door, variable Open = 1 and if only one Player s not on it then Open = 0