If you earned 7 Stars for play in 2014, you can designate someone for your 7 Stars companion card. If you did not make 7 Stars for your play in 2014, and you make Diamond Aspirations 2 (80,000 tier credits) in 2015, you can designate someone as your Diamond companion. If you then proceed to make 7 Stars in 2015, you can designate domestic ne else as you 7 Star companion.
You can only have both companions if you were not already 7 Stars.

This is the info I was given at the TR Desk in Paris, January 2015. I made 7 Stars for the first time during the summer of 2014. I had given someone my Diamond companion in April 2014. I was able to make someone else a 7 Star companion in January 2015.

The person you designate as your Diamond or 7 Star companion needs their own TR number and must be with you at a TR desk.