I’ve put on the second heddle kit and had a play to see how it works for 3 shaft patterns.
To warp it for this purpose you need 3 ends through each slot. As I used direct warping I put 2 through one, then 4 through the next. After threading the first heddle I then had 2 through each slot and one through each eye.
I put on the second heddle and then took the one through the eye of the back heddle through the slot to the right, the two through the back slot were then split, one through the slot directly in front and one through the eye of the front heddle. It is important not to have any ends crossing between the heddles.
Once warped I had a play to determine how it all worked:
Front up – back neutral the end through the eye in the front heddle is up, the other 2 are down.
Both down, the end through both slots is up, the other 2 are down.
Alternating those 3 positions produces the following:
Now to have a play with mixing up the order to see what happens.