Whenever I have had to introduce a new dog into the family, we walked them both (one person with one, another with the other), just being very casual with them.
Cedar is probably just very nervous about being around a larger more excited dog. Try low-energy activites with both (having other people with you too), and show Cedar that things aren't so bad.
Congrats on your new pup!! Love to see pics whenever you get some
Take care and enjoy your pups!