How to create and run sessions concurrently

sometimes I have close to 100 pdf open in Sumatra. That makes it hard to navigate through the documents.

Ideally one could create sets of bookmarks (as in a web browser) and only work on one set at a time.

Another possibility would be to create say 5 sessions and have 5 instances of sumatra open each separate session.
Can this be done?
First, let’s say I have pdf1, pdf2 and pdf3 open an I’d like to create a session with pdf1 + pdf2 and another with pdf2+pdf3. How do I save the session?

Then in order to run several instances of sumatra, they could be run as self-contained portable programs - I could have 5 portable copies installed, right?

Yes, you can have any number of portable copies in separate folders/directories, and each will remember the files opened in it as long as “Remember opened files” is turned on under Settings.

If you search this forum and github issues you will see some suggestions as to using batch calls or simpler alternative shortcuts to change groups of https://forum.sumatrapdfreader.org/search?q=session settings. One useful command that is not documented is -appdata such that you can have one sumatraPDF.exe with multiple SumatraPDF-settings.txt in seperate files

For example lets say you want settings for day and night or accounts and comics
You need separate folders to keep the settings
one might be c:\sumatrasettings\day the other c:\sumatrasettings\night

The choice of location or name does not matter (keep it simple and try to avoid spaces)
then copy your shortcut and amend the ends of properties to point at each folder

“c:\program files\sumatrapdf.exe” -appdata c:\sumatrasettings\accounts
“c:\program files\sumatrapdf.exe” -appdata c:\sumatrasettings\comics

If you have 5 groupings then make 5 folders for your different histories