As it has been said: You can't force a RealTrack to play what you want.

But: You might try to trick it into playing your melody by carefully selecting the chords. Maybe not the entire melody, but a major part and a note here and a tone there off the intended melody line. Then Melodyne might be helpful here. This depends a lot on how complex your melody is, but there is a possibility.

If you have your melody, freeze it and reset the chords so all other band members don't try to play the melody also.


Desktop; i7-2600k, 8 GB mem., Win 10 Pro, BIAB 2017; RB 2017 - latest build
Laptop: i5-2410M, 4 GB mem, Win 10 Pro, BIAB 2017; RB 2017 - latest build