Is it possible to insert Note Ties to join identical notes (so that the time values are added together) ?

I’ll have to try this later.

What I do is go into Editable Notation Mode, delete the second note, right-click on the first note and lengthen its duration. BIAB will automatically notate it, including ties across a bar.

Some use the Piano Roll to accomplish the same thing.

I generally use the Piano Roll method. The 'length' of the note is slightly more visual.