If you only had two masters, it would be much easier 
But you have six and that was not even possible in FL5.
Have you read the Multiple master tutorials? https://glyphsapp.com/tutorials/multiple-masters-part-1-setting-up-masters
If you only had two masters, it would be much easier But you have six and that was not even possible in FL5.
Have you read the Multiple master tutorials? https://glyphsapp.com/tutorials/multiple-masters-part-1-setting-up-masters