You could work from an imported existing midifile, or edit the melody manually into the Melody track too, for guidance.

Melody midi channel use in BIAB is normally ch 4, in the downloadable session files below it might be ch 1.

Midifiles and printed stuff:
http://www.bluegrassbanjo.org/e-k.html
https://thesession.org/tunes/1812

PS using Halion Sonic SE (free) as Midi sound goes, this VST might give you a better sound source.

In Monroe's recording with Kenny Baker there are also some slight tempo slowdowns on the breaks, you could do that via Bar settings (F5?)
Otherwise the BIAB realtracks are great for backing with Andy Leftwich as sparring partner especially.


PS saves you work?: https://www.youtube.com/watch?v=eD1Z4xIGzmc
you'll make a better one wth BIAB's realtracks however ..