It depends on who is fronting. Some are okay saying who they are, some aren't. Sometimes with co-fronting there is no clear one "who." The one writing this does get annoyed when asked. Here's a sample of responses:
--"None of your business."
--"[name of alter fronting]"
--"Who do you think it is?"
--"I don't know."

Sometimes it makes us really tired trying to figure out and identify who is out. Just let us be.

We like it when someone knows who is out and calls us by name!