bi-amping and effect on cross over

I am trying to understand the effect bi-amping a speaker will have on the designed specs of how a cross over should work. Dynaudio, for instance, does not offer up dual(or triple) binding posts because they feel bi-amping would negatively effect the way their cross over is designed to work.

with my simple knowledge of the way a speaker crossover works, it sort of makes sense to me that the speaker should "see" one amp connection and then shift highs and lows to tweeter/mid and woofer as needed. I am sure i am missing an understanding of how a crossover can compensate for bi-amping (and give the same designed crossover slope/effect but with more current to each driver). Would love some clarity. thanks.