You should be able to separate those three connectors. I have not done it so I can't offer any advice, however some of the connectors on this car require a lot of force.
Have you looked at the Becker wiring diagram (pinout)? You might be able to just insert the pins for the AUX directly into the existing plug? Unless you have a CD changer the AUX pins should be open.
Pins 13 & 14, the pinout should be the same between the 210 & 220.
Link:
http://www.discountcarstereo.com/pdf/bt-brknp.pdf
Porscha
Threaded Mode
