Do you have experience with this? I’ve been looking at it for a while. Unplugging and re-plugging a ton of cables is the thing that keeps me from experimenting more with my setup when the mood strikes me.
somebody mentioned the mrcc, if that is too big/expensive or some of the fancy things it does are not needed, they just released a smaller version:
can merge and split.
There’s a device available on Amazon called “4i4o” sold under various brand names that may be sufficient, 2 in, 4 out, when in a split/merge configuration.
TIE 4i4o Interface with MIDI-Merge https://amzn.eu/d/88dwfuI
i got one and am quite happy with it. routing is very easy and quick, probably the best of any midi router, rest of the interface is a bit “engineers making UI” but workable. you can save presets for experiments.
it replaced 6 little boxes that i used four splitting/merging/usb hosting, where i had no idea what was going on after setting it up. 
After discovering that there’s old 40-60 dollar midi routing units with no usb and a built in preset that does exactly the basic thing they are trying to achieve, it blows my mind people still consider a thru and a merge box for 2-3x the price.