If original form was done within Catalyst, you could create a new page state that you transition to when the button it clicked. However, you will still need to transfer your project into Flash Builder if you want the form data to be sent to a server.
I uploaded a quick demo that might help.
Thank you for your prompt response... and thank you for the demo file... was I suppose to open the fxp in FC or in FB?
I created both forms in AI and want to use both on the same stage in the swf... The first one is a larger form and the second is smaller subform that I want to display over the first form after clicking a button on the first form... Can this be accomplished in FC or do I have to just use Flash Professional?