I am struggling with mesh vertex welding. Select the two vertex activate the command and the two vertex remain separated. In rhino5 I had no problem with that. Anything I miss?
maybe _stich does the job in your case ?
otherwise you might want to post a file or at least a screenshot.
This command does not exists in my Rhino 6.
I have tried both _stich and _stitch
weld.3dm (2.3 MB)