How to Fit a Hackabit

I just bought a happy mouth hackabit as an ~experiment~ and am not entirely sure how to fit it.

i bought this one:…1-adType%5EPLA

dont worry, ill be having my trainer help me. i’m just a bit confused because the hackamore part is jointed and moves independently from the rest of the bit. i tried it on my horse today (in the stall, he’s on stall rest currently… but that’s another story) and it seemed like pulling on the curb ring had no impact on the hackamore part whatsoever. now, i plan on riding with it in 2 reins, and it seemed like the hackamore would only be engaged with the snaffle rein on the big ring. this would give the hackamore part very little leverage, and it would act like a bosal hackamore.

is this correct? i’m a bit lost as i have no experience with a hackabit