Unfortunatly, this is not possible today.
However, we may add this new feature in some future.
About the syntax, we are think about using an initial character (like / ) that would suggest to
the layout engine to not break the line.
This would allow:
note over Alice : initial state of Alice
/ note over Bob : initial state of Alice
Bob -> Alice : hello
This syntax seems flexible enough to allow simultaneous messaging:
Alice -> Bob : hello
/ Bob -> Caty : hello also
However, those modifications require some refactoring of the layout engine (especially the last one).
We will post a news here when multiples note will be working.
Any sugestion about the syntax ?