This is the implementation of what is explained at https://wiki.archlinux.org/index.php/PulseAudio/Examples#The_shell_script_method with specific improvment related to the Behringer UMC404HD interface.
Everything there has been tested on UbuntuStudio 22.04 with the 4 inputs and Roland RD-88 added as analogic sound source + midi interface.
You must have a look at pulse-jack-post-start.sh and read comments.
In my context the post start script works with zsh as shell. If you change it to bash, it may not work, as it is the case for me. I don't know have time to inspect how qjackctl is launching those scripts. My $USER is set up with zsh, and putting #!/bin/bash in the script has no effect on the $SHELL env variable. After investigating why it was like this, replacing #!/bin/bash with #!/usr/bin/zsh made things work, but there is a mystery.