Hi,
first if you work in different bands in the OT I would have a seperate set for each band. On the A4 I would have different banks per band.
Second, if you like to play the A4 via an external midi keyboard I would
syncronize the OT (master) and the A4 (salve) and than play the A4 with a multi chanal midi device (two Midi in (keyboard, OT out) to two midi outs (OT in and A4 in).