Multiple external swf preloading

Hello everyone,

I have a main file,which uses an empty movieClip as a loader,for the external swf files.I also have some buttons,which load each external swf(4 in total).
Is it possible to preload all the external swf files,before playing them,instead of creating a preloader for each of them?I am working with AS2.
I searched a lot,but nothing worked for me.

Thanks in advance.