There are only two on the MB Pro. One is connected to a StarTech Docking Station, and the other is connected to a 2nd external monitor. I also need to connect a firewire audio interface, which I have a FW to Thunderbolt adapter for. The problem is, I'm out of thunderbolt inputs, and apparently there is no such thing as a Thunderbolt hub as there was for USB. What can I do to add another thunderbolt input?