Existing parked up players don't get shifted to a new instance to make room for a new entrant. Usually the peer to peer instancing hits it's capacity before a large station's pads do, and anyone new to the station will find themselves starting another instance.
I've had this often in busy systems, like CGs, where I've followed anything up to half a dozen other commanders across a system, watched them all drop down in front of me and when I come to do so find myself in a completely empty instance, which then slowly fills up with the people following me.
Smaller locations like outposts, megaships and engineer bases can have their pad capacity overwhelmed, often resulting in a queue for the pads.
I've had this often in busy systems, like CGs, where I've followed anything up to half a dozen other commanders across a system, watched them all drop down in front of me and when I come to do so find myself in a completely empty instance, which then slowly fills up with the people following me.
Smaller locations like outposts, megaships and engineer bases can have their pad capacity overwhelmed, often resulting in a queue for the pads.