Help! - multiselect userform listbox with dependent drop down

[bossroy]

Hello,

I am attempting to create a content control drop down that has options dependent on selections made on a multiselect userform listbox. I have a functioning listbox but cannot figure out how to create either additional dependent listboxes or drop downs. I have attached a copy of my current progress.



The existing listbox will end up with more than 25 options and the same goes for the dependent drop down I am hoping for. I have searched existing threads and cant seem to piece this together. Any help or direction would be greatly appreciated!