Quote from Martin in Lilith Needs a Favor
Martin: Can you imagine? Lilith's and my kid would be brother to you and Niles and Freddie. Frasier: What are you talking about? Martin: And if you and Lilith got back together, you'd be his step-father and his brother and Niles would be your son and his own uncle. It's almost worth doing just so that I can tell the story.