Conversation so far:
When did he reunite with Lilith and Frederick?
In "The Show Where Lilith Comes Back" (1994), Lilith surprises Frasier by dialing to the radio show.
What does she say on the radio show?
They later make love in a hotel room, but end up regretting it, prompting them to part ways again.

Question: Is he reunited with Frederick?
Self-contained rewrite: Is Frasier Crane reunited with son Frederick in the Frasier episode "The Show Where Lilith Comes Back"?