I've always believed that all roo girls have their pouches as infinity pouches of holding, but that they also are linked in the P2P or Pouch to Pouch networking protocol, allowing travel and storage between them, making it handy to stick your paw into pouch to access the contents of another. This could be awkward though for the receiving flyer when someone's paw abruptly appears in their pouch to rummage around.

 vladira_bloodmoon, aka Fluffy Bloodfang, has found size shifting down to dive between pouches as a handy means of travel.