Hi, e! FileMaker 3-4, 5-6, and 7 all use different formats so are not compatible with each other so try converting a copy of the FM6 db to FM7 and then copy/paste and see what happens. I typically do not copy/paste from db to db though so I'm not sure it will work even then. For example, what will happen if you paste a field that does not exist in the new db? Or what if the field is named the same but is of a different type? Well, at least converting to the same version should help, though.
To answer your question, if a field does not exist in the new db, when you paste it keeps the field as a blank field. You thne have to attach it to the new field. I have done it before in the same version, since we use a standard format for headers and stuff.