Hi

. . . .when I import I get a prompt  that asks if I want to add  a new project.. . . .

It would appear from the message that you are trying to combine two projects together - in which case you do add the second project.  This will give you two movies in one project.

Depending on how you want to combine them, ie do you - (a)  want the two movies combining into one or (b) do you want the two movies independant of each other but on the same disc. 

In the case of (a) you copy all the objects from one movie timeline and paste them in to the other and then remove the unwanted movie using File, Manage movies, Remove from Project.

In the case of (b) you keep both both movie timelines and MEP will take care of the menus for DVD / BD.

However from this post and previous posts I feel your workflow is making things more complicated then is necessary and it is also possible that the camera editing is destructive to the original video.

MEP is a non destructive editing program, so you can capture the video from the camera in one go or in segments if you prefer to your computer. 

You then import the captured video into MEP and cut it as you require, reorder if necessary, add effects, titles etc and export the video or burn DVD's or BD's, without destroying or changing the original captured video.

This way you do not have to go back to the camera to re-import parts of the original recording you later decide you need.

HTH

John