UR28M and External Mixer (I/O Limitations)


I’m using UR28M for year and a half and totally satisfied with this soundcard. Build quality is outstanding.
In my little bedroom studio i have Behringer Deepmind12 and Neutron, but recently bought Boog. After reading UR28M manual with I/O section, i realised that i can’t use all my synths at once because of I/O limitations. (Soon wan’t to buy drum machine and another synth).

I searched a lot for this topic a lot but cannot find any decent solution.

So my questions are:

1. What i can buy for expanding my I/O for live jams or recording? First of all i think of Mixer (Behringer XENYX 1222USB, ALLEN & HEATH ZED-10, MACKIE 1202VLZ4 or SOUNDCRAFT SIGNATURE 10).
But i don’t know how to properly connect UR28M to external mixer so all my hardware synths are connected to mixer, but main audio would be my UR28M soundcard for recording, especially if i can use them separately in Ableton Live 10 (via External Instrument) in separated channels to be able to mix between hardware and software worlds (don’t throw at me, i’m new to this field, always been DAW producer and constantly learning in this area).

2. I watched video with Behringer RD-808 and saw they connect all outs from drum machine (Multi Channeled) into Behringer U-PHORIA UMC1820 and all outs been separated individually in Cubase.

Can i use this method with my hardware synths (as i mentioned in my first question), or it’s only for controlling outs from some gear (for example RD-808 or old Roland 909) into DAWs for recording?
The only thing that comes to my mind is that I will not have much control over EQ section / External guitar pedals effects and etc (i know i can use VST type effects, but wan’t to do it outside my PC, only to record individual channels into my DAW and then only tweak audio afterwards).

Would be much appriciated for any help (especially with pictures, videos or courses) :unamused:
And sorry for my english if it is (not the native speaker).

Thank you!