I thought I knew how to do this, but I forgot

I have an external synth on channel 14, and want to record on channel 10 ( for the reason I actually want two sequencer tracks both controlling the external, 10 and 14.)

I know I can first record track 10, and then change it's transmit channel. But if I want to hear the external synth, and I change the transmit channel before recording, it won't record, because it's transmitting to the MIDI channel 14, and the sequencer wants the MIDI on channel 10.

I could be wrong, but I thought there was a way to record to the internal track after changing it's transmit channel.