Using a 32bit audio channel to transport 2 16-bit audio channels, preferrably with ffmpeg

I have been looking for this a lot, and seems to be either really stupid or really insane idea, because I can’t find anything about it…

I have the problem that I want to push 3 or 4 channels through a system which supports only two, but at any depth. So theoretically I can use the low 2 bytes of the left 32bit channel for one audio channel, and the high two bytes for another, ditto for the right channel, and actually carry 4 channels (and unmix them on the other side).

If I don’t do floating point and integer only, there should be no loss, and I don’t intend to listen to it while in the system, just when it’s out.

Any ideas if something already exists for this type of muxing/demuxing?