Comment 2 for bug 1717877

>I am interested in looking into fixing this issue myself, but I would need a bit of tutoring (to help locate where the relevant pieces of code sit in the repo).

To locate the relevant path in the code of any action, start in verbs.cpp (ctrl+f combine → "selection->combine(); line 1281)
This is a method of the selections, and selections are objectSets (selection.h:60), so you'll have to look at object-set.h, which has an helpful comment at line 400 telling in which cpp file it's implemented.

→ it's in src/path-chemistry.cpp , lines 54-192