Upvote:1
You can show a reservation that differs from that which you provided with your Schengen visa application, but should use some caution in doing so. If your friend's hotel reservation does not include your name, ask that it be added. You may create a problem cancelling what you submitted with your application, and showing one in the name of someone not related to you, and not mentioned in your visa application. If you're entering in Frankfurt, and immediately going on to join your friend in Paris, that evidence of accommodation should be all that you need.