If you don't want a natural seventh, then don't write the Maj. Anytime you write Maj7, it will always be a natural seventh. CMaj7+11 is C-E-G-B-F#, CMaj7b5 is C-E-Gb-B, C7+11 is C-E-G-Bb-F#, C7b5 is C-E-Gb-Bb. All of these chords are available in iRealPro. Later, Ray