Originally Posted by JerryFF

Here are some specific answers to add to the general remarks already provided.

Yes, CO miles can be used for other Star Alliance members.

No, you do not have to join each individual Star Alliance member program. In fact, you should try to have all of your Star Alliance miles deposited to one account. If CO is your favorite, then put your CO account number in the reservation whenever you fly a Star Alliance member. That way you will reach elite status with CO and get added benefits. Check the CO website to learn about the benefits of elite status.

The miles you have already flown would have been credited to the account for which the frequent flyer number was entered. If your CO number was entered, then those miles should have been credited to your CO account. If no number was entered, then no miles were credited anywhere. If you didn't get credit and if you still have your boarding passes for these flights, you can send the boarding passes to CO and request credit.