Extra Sidebar Widget?

Hi. I was wondering if there was a simple way to add an extra left sidebar widget to contain a custom menu. I already use one left sidebar on some pages for a secondary custom menu, and now my client wants me to add a different secondary custom menu on a few other pages. I’ve seen the documentation for adding an extra header widget, and have put that code into a child theme function.php file. But now need an extra left side bar, or something to that effect.

Basically the site consists of about 30 pages. Most of the pages use no sidebar: full width layout. 5 pages use the left side bar layout that has the first secondary layout in them. I need 5 other pages to use a new left sidebar layout with a second secondary menu. Or if there is a suggestion for a totally different/better way to do this, I’m all ears. Can I use the right sidebar and somehow reposition it to the left with css? If so, that seems like the easiest option.

Also, if it helps, I am using the PageBuilder by SiteOrigin plugin to help with building the site in columns and rows of information per page. Hopefully this makes sense.