You can export the person or family as a gedcom from the one file, and then import that gedcom into the other file. In the second file you will need to link the imported person or family to relatives that are already there.
If it is just your own name, birth, and marriage, it will be easier to type it into the other second file. Creating the one additional record should only take 5 minutes.
... if I understand what you have in mind.
If you need to move a bunch of people from one file to another, I found Family Insight ($25 from ohanasoftware.com) to be worth the money in saved time.