1.  A visit to the ISS will be a life-changing experience which you'll never forget.
2. Both Ted and Tony have won a medal.

1 A visit to the ISS, which you'll never forget, will be a life-changing experience.
2 Both Ted and Tony have won a medal.

1. A visit to the ISS will be a lìe changing experience. You'll never forget this experience(WHICH)
-> A visit to the ISS, which you'll never forget, will be a life-changing experience.
2. Ted has won a medal. Tony has won a medal, too(BOTH)
Both Ted and Tony have won a medal.