Project within a Project?

Im sure you've heard this before. Im not a Flash coder but have done extensive work back in the days before AS. Now I thought my task was simple enough.
I was asked to create an interactive touch screen kiosk and of course Flash was the tool of choice.
One particular module was way beyond my scope so we opted to purchase an FLA file so we can add it to our existing FLA project.
Well strange that I cant seem to get this FLA project to import and work (at all) within its new home.
I tried copy and paste and Open Library and nothing.
I did my research on the internet and it seems to be a tricky but doable thing.
I dont have any AS3 knowledge but Im assuming that I could have selected an "open MC" option within the authoring tools.
Well I gave up after a few weeks of trying. I know when Im beat.
So my fix was to edit the problem FLA file and turned that into the main FLA file by resizing the stage and moving layers/frames around to accomodate the other parts.
Now of course I tested did this with a few frames and it does work.
However, I would like to avoid spending another month rebuilding the whole interactive just for this one albeit important widget.
Anyone care to smack some sense into me with this one :)