We did a code share with Jet Blue and Silver in May.
Multiple checked bags for a couple of the crew without a problem and plenty of room in Silver under seat and overhead.

However, the boarding passes issued by one airline for the other did not work either way.
We sure to have the airline check/reissue your connecting flight boarding passes in SJU.

FYI: Jet Blue credit card free checked bag policy does not apply when connecting to a non-Jet Blue airline.


Chuck W.