Kerdi Fix to seal niche instead of kerdiband?

[90Moneypit]

Hello,
So I've searched Schluter's site and here but I can't find an answer to this question.
Big question now is: Can kerdi fix, which I'm using to adhere the top and side panels to each other for shower niches, ALSO maintain the waterproofing or will I still need to use Kerdiband at all 4 inside and outside corners?
I'm using kerdi board for walls along with their shower pan and curb with everything cut and ready to install except... I'm making my own shower niches. I have more than enough scrap material in the way of 1/2" kerdi board to make 3 separate 12"x24" niches including 'homemade' kerdi shelf dividers. The plan is to make the niches with the top and sides still connected on the facing side (think plus sign shape except it's a rectangle) and the shelves are 12x9" with the backing mitered for corners reinforced with scrap 1" foam from the shower pan.

It's driving me crazy, that and the lack of clarity over using membrane over a kerdi-fixed hole around a protruding pipe (yeah, oddball single handle horizontal to the tub spout).

 

[Jadnashua]

If you get the edges of the Kerdiboard sealed with KerdiFix, you should be fine. The foam itself is waterproof, so gluing the niche together with KerdiFix will maintain that...but, the top and bottom layer could allow some moisture to get in between that and the foam if it isn't also sealed well to the adjacent board.

On Monday, if you can wait, just call their help line...the people there are pretty sharp. FWIW, the factory niches are glued together, but it's not KerdiFix, they use something else (don't know what it is). It's probably something that sets up quicker.