Linking travelers profile would also allow to send all messages to each one automatically.
References should not however be forced to be for the whole group, but it could be just an option, otherwise the person has all profiles redy to get the reference.
Same for hosting reference, when one is hosted by a group.
Yeah, could be nice to have an option to add smth personal to each reference! Or even to write different ones if you want. Probably more difficult to implement though?
I was thinking differently: each reference must be always written to a single person, so you can completely personalize, the only option would be a button that just copy the previous reference in the edit area, just to help those whose devices make C&P inconvenient.