about the 1/4" (6mm) switch jacks on the back.
Page 6 of the manual will tell you that on the BCR Switch 1 is a Tip Ring Sleeve (TRS) or stereo jack socket as it is more commonly known. Switch 2 is just a 1/4 Tip Sleeve or mono socket.
You can use Switch 1 for both switches on a single cable by wiring the tip to one switch and the ring to another and the the sleeve to the common tags on both switches. Usually microphone coax cable is used with the ground shield used between the common tags and the sleeve.
Tip -----------\
Switch 1
Sleeve ------|-
Switch 2
Ring----------/
This doesn't mean you can have 3 switches. Switch 2 becomes unusable.
The FBC1010 has a relay in it's footswitch output and so you can connect it to the footswitch in on the BC2k.
I gather that Behringer are about to release a 2 switch pedal that will work perfectly as well.
Also their V-Amp series came with an identical 2 button switch.
All the best
Royce