Thank you for your reply. I think I can understand what your saying. I know that I have this picture of a great family that works fabulously and everyone is happy together, etc, etc, etc. The real world usually has a couple hiccups along the way, and I can imagine so does the poly lifestyle.
I think your advice about keeping an open mind, and not being completely fixated on one outcome is very useful.
Update: We will be telling our parents (mostly very conservative people), about our desire to move forward with this type of family change. We hope it goes well, but are preparing for the worst. Its important for us to include our family in this process because they mean so much to us. Their input and feelings will have value, so wish us luck!