Bookmark OS offers powerful tab managment to help make re-visiting tab sessions easier. You can create "session folders" which will open any bookmarks inside into new tabs when opened. Otherwise "session folders" behave like normal folders, so you can drag bookmarks inside, change the order of the tabs by sorting the "session folder," move the "session folder" around, etc...
Let's say you have a bunch of tabs open that you want to group together and save. You can do this by saving all these tabs to a session folder. When you open a session folder, it will automatically open every bookmark inside into new tabs so you can restore your session of tabs. To create a session folder, click the "Save to Bookmark OS" browser extension button (in the upper right of your browser) and then click the "Save tabs" button in the bottom right.
You will then be able to remove individual tabs from the session:
You can also turn an existing folder into a session folder. To do this, right-click the folder and select, "Edit" then click, "Make tab session folder" and then click, "Update folder."