question

I don't think you should try to use logic to define the Destination for the patients in the Create Patient activity. You should probably create all patients in a central location and then use logic to decide which elevator the patient should go to. You may not even need logic to pick an elevator. You may just need to do standard acquires and releases.

I have no idea what your intent is for using "center port connections to keep this from happening?" Center port connections are simply a modeling technique for being able to get a reference to another object that you've connected to an object you have a reference to. There's no magic with center port connections. It's just a tool for referencing another object!

So anyways, try my idea above and see if it helps you come up with a better modeling solution. If you're just playing around for learning purposes, you might want to play with the actual elevators. They work well with the A* system and multi-level floors.