M:S midi thru playability

Hi! After lots of experimentation and moving around, I have found a compact setup that works for my live shows. Excluding mics and pedals, it looks something like this:

keystep —> M:S —> Volca FM

I would like to sequence the Volca FM with the M:S sequencer, but instead of using the rubber buttons I wanted to input trigs via the keystep. After some menu diving, I managed to be able to get the midi signals thru, but with some problems.
When the midi settings on the M:S are set on thru, I can play the keystep into the volca, but the M:S sequencer won’t work (I have sound as long as I press keys, but no sequencing); whereas when the midi on M:S is set to out I can hear the sequencer working on the Volca FM, but nothing happens if I play the keystep (sequencing is on, but I can’t play live).
I am working around the issue switching constantly between midi thru and midi out on the M:S, but I was wondering if there was a way for me to sequence the Volca FM with the keystep, going thru the M:S. I hope everything is clear enough!