Linking between external SWFs


I’ve looked through the discussions here but can’t seem to find exactly what I’m looking for. I have followed this tutorial:

So I have my main movie and external SWFs get loaded into it. I want to put a button on one of the external SWFs which will link to one of the other external SWFs, but still keep them both contained within the main movie so I don’t lose the main navigation.

I can’t work out what code I need to use to do it - and whether it needs to be in the main moive or external SWF. I’m sure its something really simple but I can’t get my head around it!

Thanks very much for any help.