I think this might be the best add-on I've ever installed (apart from uBlock Origin ofc). I'm way more organized with this, it's a life-saver!

I do have some suggestions though, the first of which is to have the option of making a tab (or tree) the first child when dropping it on a parent tab (I like to have my latest tabs at the top of trees). This should also go for when a link or string is dropped on a tab (Drag and Drop section).

For my second suggestion, I use an extension called "Search by Youtube-Right Click Menu" and when I look up a term with it, the newly opened YouTube tab is considered an independent tab whereas I would like it to be first child of the current tab (other options would be nice too!). I've tried tweaking the "Tabs opened from Existing Tabs" and "New Tabs not from Existing Tabs" settings but none of them seem to do what I want. I'm not sure how these tabs behave but if it's possible to implement this, it would be pretty cool.

And for my final suggestion, I think it would be nice to add the option to make all the descendants of a tree the first children of said tree. Sometimes, I just keep on creating new tabs which create a new child of a child of a child, etc.

Thanks!

PS: I apologize if those options already exists but I looked for them in the settings and the Extensions extend TST list but couldn't find them.