2 midi tracks merged into 1

Hi all, I've got 2 older midi tracks- 2 piano rolls & 2 separate vst's. I want to merge these as one to use in Kontakt in the parent midi folder. I seem to remember doing this once before, but I can't seem to get it working now. I know I'm missing something simple and I can't find it in the manual or here on the forum. Thanks...

Thanks again DS, you're very helpful, as always! That worked, but it would be cool to have a 'merge' option rather than glue. Maybe I had the terminology wrong... Parent folder> MIDI track (Kontakt)> instrument tracks.

^^^^ That looks OK to me