Routing question with external mixer

If this question has been asked and answered before, please bear with me, this is unchartered territory for me, so I’m not sure what keywords to search for:

I just bought a Waldorf Blofeld and realise that I have run out of inputs on the UR44 (two monosynths, a mic and a guitar fx pedalboard with stereo outputs), so I believe I need an external mixer.

However as I have an external reverb unit (Strymon BigSky) I’d like to send plugins through the mixer so I can get the nice reverb (send) on them as well.

Which brings me to the core of the question:
I route output 1 and 2 on the UR44 into the mixer, then the output from the mixer into line inputs 5 and 6 on the UR44? Then I need to figure out how to set this up in Cubase, but that’s another story.

Am I understanding this correctly? Am I on the right track?

I would suggest to use output 3&4 as send to the mixer.
So you are still able to use the main volume knob for the listening level.

Make sure that the mix 2 (or the mix you are using for the send) is not getting the mixer signal, otherwise you will produce a feedback loop.

Start reading… please!

Yes, I did that (add input and output buses in Audio Connections), and still it doesn’t work for me, which is why I ask.

EDIT: I asked this in a separate post here: I did that, but I get no bus alternative in the routing section in Mix console

Don’t know what this means. Screenshots? Audio connection windows…

Thanks for helping me out, these are my audio buses (in/out) and the routing section.
And, there is nothing to select (no dropdown menu or anything) in the routing section:

Screenshot 2023-08-19 at 14.37.28
Screenshot 2023-08-19 at 14.37.36

The in and out buses need tracks to get routed to or from.
Without tracks, there is not much sense to route anything.

Thanks, like I said, this is completely unchartered territory for me.
I was under the impression that I could do that on the Master bus out, route first output 3 and 4 on the bus, then in the slot below in from 5 and 6.

But can I do that on a single audio track? Or do I need two separate tracks, one for out, another one for in?

I finally got it to work:
The easiest solution was route out on 3 and 4, then in on 1 and 2 (because the mixer out had low output so some gain was needed).