Hey Joisan,

Taking a dynamic dress and making it conforming will take you down a very long road.
The dress will have to be "rigged". This consists of placing 'bones' in it and defining how it bends with fall off zones.

Best to search this forum (and the tut area) on the topic of rigging.

I don't know how to do it, but at least I'll try to point you in the right direction.

Good luck!!

 Don't sweat the petty things, and don't pet the sweaty things!  ; )