Formatting Solo parts

So I am trying to add both a solo cello and Cello section part in the end of my score. What I want is to have the two parts break off into a bracketed section.

(like this, but imagine its a cello solo, with the normal cello part right below it)

I have tried to create a new part in the score, then putting the section part in that new staff, then selecting "Hide all measures that do not contain notation (Cutaway)" . This "Works" To a point for me, however it tends to lead to major formatting issues throughout the score (It will hide the staff/part however it will still format the page as if the staff was still there.

(This is my situation, I have the main solo part on top, however the 2nd voice i need to be a section part.
How can I separate these, or how Can I have 2 different instruments in the same staff?)

I just need some ideas on how I can implement a proper bracketed section where I can have a solo, and non solo part connected together. thanks!