100BASE-T two devices on a single ethernet port
Is it possible to wire directly from the PCB's of device 1&amp;2 to a single rj45 mag port


You mean, the magnetics inside the RJ45 housing? No. That is because there is no such thing as a "rj45 mag port". There are a dozen different layouts of magnetics out there and you have to pick the right one for the devices' transceiver.

What you are trying to do is to find a RJ45 connector which has the correct magnetics for device A on pin 1,2,3,6 (ok) but instead having auxiliary connections on pin 4,5,7,8 (anything from magnetics ground connection to resistors to POE feed) it should have another set of Fast Ethernet magnetics as needed for Device B pin 1,2,3,6 BUT on Pin 4,5,7,8. Good luck in finding such an abomination.

The only chance you have is to separate the magnetics from the RJ45 connector.