Hi aptiger!
Adding individuals at AUs has it's negs and benefits. Each of you will glean the credit history of the cards added. Depending on your profile, it could hurt or help you. For example... if you decide to carry a balance, the extra padding of the AU's unused credit limit can help with utility. However, if the credit history of the cards added is lower as an average then yours, it could affect your overall AAoAs and lower your score or move you to another bucket. In the end... you can always remove yourselves from each other's cards if you find it negatively affects you. It could affect one positively and the other negatively or both positively or both negatively. You won't know till you do it. I hope this isn't confusing. Remember... all the good and bad will affect both reports. I hope this helps. 
Starting Score: 642