Pets are a wonderful addition to the family because they make great companions.
Pets are a wonderful extra member of the family because they are/prove to be great companions.
For me, the second reads better than the first sample in that an addition comes across as indifferent apethetic object to the family while a member a living and kicking family.
As for make, I can't figure out why it's used in the context.
Your comments? Thanks.
The first sentence is your better choice.
I understand your sentiment regarding 'indifferent apathetic object', but I respectfully disagree with you. Let's look at it this way: On Monday, there are 4 members of the family. On Tuesday, the family buys a new puppy. With the addition of the puppy, there are now five members of the family. The only way to increase the family size is to add a new member! The addition of the puppy demonstrates the family's desire to share their home, and their combined physical and emotional resources, with another living soul.
In your second sentence, how can you have an 'extra' member of your family? One is either a member of the family or they are a non-member of the family. To say that the puppy is an 'extra' member of the family serves to highlight the 'indifferent apathetic object' qualities that you are trying to avoid!
The word 'make' in this instance is synonymous with 'become'. When you make friends with your neighbors, they become your friends. Puppies 'make' great companions because they 'become' great companions.
Have I rambled on too long? I hope the examples I provided are helpful.
Thanks, Naamplao and Amigos, for clear and helpful explanation.
I got it now.
Amigos, I really appreciate your patience and examples. They are priceless!