Collision Movement

Hello,

I'm trying to create a library of my design work, for perspective clients and I've created a common gallery type, with scroll function, nothing fancy.
But I want to know how to make one mc move along when another is toggled , at the moment I have extended a white background on each movie so that the layer below doesn't show up when the movie is interacted.

The structure is a parent movie that calls up the other movies within different mc holders, now i guess that this structure may not be adequate for what I want. I have investigated collision movement but I'm not sure how it can function within my structure.

Thanks for any help