There's no point in having 2 trees of the same family. Trees can't be linked. You can try to export both in GEDCOM format and merge them. Use Google to search for "GEDCOM merge" (software: GenMerge, GENMatcher). Reimport merged trees as one. But as you probably know, you need to add the pictures again... for every memeber that already had one.
The members with no firstname will be displayed as "Anon" instead of "Mother of...", "Father of...", "Children of..." etc.
