How to split message body in multiple messages/thread ?

[Darksky]

I explain better.
THere's a message and i want that my moderators can split the single message ( and not the thread ) in differente messages or thread. The same that happens with thread splitting but i want this feature applied to single message.
For example, my moderators can select part of a messages and cut and paste it in a new thread or message. This new thread or message should appear as it was posted by the original autor of the "mother message" and not by the moderatorl

Does exists a plugin to make this ?

I'll appreciate for any help