I don't know for sure if this idea works or not, but here's the idea;
Place one JSCH in one client (I'll call it S1), and the other JSCH in another client. (I'll call it S2). Use the TransportCase facility to export S1. Then use the TransportCase facility to import S1 into the same client that holds S2 with the "replace" option.
I seem to remember that the TransportCase utility is smart enough to merge objects that contain lists of items. I know I've seen it work this way with static variables. I don't know if it will work with JSCH objects, but maybe it will?