I'm looking at the Joie Excursion Change & Rock travel cot. I can see there are also models called Excursion Change & Bounce (or Snooze & Bounce) which have a bouncer attachment instead of a rocker. If the base unit is always the Excursion and all the attachments use their Secure Click fastening, I assume that the attachments are interchangeable and, if I wanted, I could buy the bouncer attachment separately? But I can't see this confirmed anywhere so just wondered if anyone knows for sure!