I'm not sure if I understood your question correctly. Also I don't know the official mixing taxonomy very well... Maybe you will want to make a little diagram with the desired signal flow?
Well, I might try to already give you some pointers. In renoise, you can very liberally use #send channels to do parallel processing. You cannot do the 2-channel sidechaining in renoise though, only sidechain methods are signal follower or keysynced envelopes from LFOs or such. I find them very powerful already, they just work a bit different than the classic sidechain workflow.
So let's try to have a simple example, a reverb. You can place a reverb chain that output 100% wet (turn down dry) in a send channel. Then you can send from track, and sending has the option to keep the signal. So then you got the 100% wet reverb signal from the send channel, which is like a seperate track that you wished to use, and the original (dry) signal is still available in the main track you sent from. You can also send to the reverb from other tracks with sends - the reverb will be from the mix of the channels sending into the reverb send. You can even send to the reverb bus from other send channels. Also you can send from one track (or send channel...) to multiple other send channels by using multiple send devices, just make sure all send devices (but maybe the last, if you wish to mute the dry signal) have the "keep signal" active. You cannot feed back to track though - I find most problems are easily solvable by doing a parallel processing tree with send channels. But this enables some pretty cool techniques, like eqing a reverb differently than the dry signal, stacking reverbs in a different way than is possible the traditional way, sidechaining the reverb in a different fashion (strength or envelope) than the dry signal, etc.
Reverb is an easy example, like delay, but the dry/wet capabilities don't apply to all kinds of effects. Or full effect chains. sometimes it works ok, but sometimes mixing back together with the original signal can have weird side effects. Like dry/wet'ing filters or eqs can result in phase cancellation and output a different frequency balance than expected (notches in sound...). Just play around, you'll soon find what sounds nice and what sound weird.
Maybe this already helps, or did you have something else in mind?