I wish you well with that project, Paul. I hope you can make good progress on what I think is a fascinating subject.
Unfortnately I have no signed or labelled examples, so cannot contribute.
Somehow, I suspect you may find that, as with general millefiori canes (murrine), the actual filigrana may have been made by a few folk but used by many.
Will you also be trying to get examples of similar Chinese (and other?) wares that use much the same type of filigrana? Although some people claim that the Chinese versions can be identified by the type and structure of the filigrana, I am not so sure about that. But a good, solid reference to true Murano items will be a wonderful thing.