iterm2 combine tabs into split pane

I am trying to combine two iterm2 windows into a single window with a split pane. I can combine them into one window with two tabs but I don't know how combine those two tabs into a split pane in a single tab. How can I do this? Thanks in advance for the assistance!

Looks like as of late 2022 there's no one-click way to do this, but the following works for me:

1. Split the tab or window you want to work in, creating a new, empty pane 2. Right-click in the new pane and choose "Swap with session..."
2. The pane will turn green; navigate to the tab or window you want to pull in, which will be red, and click it; this will swap the two panes
3. Close the swapped pane, leaving you with just the original window with the two panes in it