Question about summing

Hey all

I tried to split the stereo output from my Eventide Timefactor with the wet going to my whammy v and the dry going into a DSD-2 (yes I have 4 delays pedals on my board!) the outs from the whammy and DSD then were going into the Stereo ins on my Ditto x4 and then going out the mono on the ditto x4. Hoping I could sum the octave and “dry” signal.

Turns out the ditto doesn’t do summing (or maybe it does and some wise person can tell me how).

So the question is- do I need a summing pedal to make this idea work in reality? The problem is that everything after the ditto is mono and I run for intents and purposes a mono rig.

And if I do need a summing pedal - suggestions?