Use 67 instead of 7add6
Use 7add13 instead of 7add6
A 7add6 is a Major chord
How to construct a 7add6 chord?
Use the following intervals in any order to construct this chord. Start on a specific note on which you want to construct this chord from (for instance the note "C") and calculate each interval on top of it. Afterwards, you will be able to play it on your instrument.