Kliperoo,
Yes there is a auto couple between the aileron/rudder but....if the pilot inputs i) more rudder or ii) applys crossed rudder & aileron he/she can over ride it.
It is still possible (although ugly) to side-slip a heavy jet.
Crosswind approaches in Heavy jets are complex not because of the autocouple but because of sweepback.
Do a quick search in 'tech log' and you'll find a million reasons why we crab all the way until the flare.....and even then, we'd rather land slightly sideways than drop a wing to much and have a pod strike.