Writing minor 7 flat 6 chords

[Jugsy67]

Any one know how to write a minor7flat6 in the music sheet. It keeps saying it can't understand this chord? Or do I just need to find an chord sub?

 

[dflat]

Sorry it is not built-in. Depending on the other notes required (or not required) related to any melody notes, you might be able to substitute with the root based on the b3, b7 or b6, then if necessary use inversion for the bass note if you want the root aurally defined specifically.
Or use the more simpler [-b6]