I used to wonder why Maxwell was so oblivious to C.C.'s obvious interest in him then it hit me, she's always been obsessed with him and likely has always acted this way. As far as he's concerned she's just acting normal and probably just thinks she's kidding around, especially since she would have acted like that while he was married.
C.C. I didn't let his wife get in my way. You think I'm pathetic now, you should have seen me as her maid of honor.
Why does Sylvia nag Fran about giving her grandchildren when Fran's sister has two daughters? It'd make sense if she said she wanted more, but sometimes the way she talks, you would have thought she had no grandkids at all. But as you re-watch the series, it makes sense: Fran is the Favorite child while her older sister Nadine is the child who was conceived and pushed along the Shotgun Wedding Fran's parents needed. There were times where Sylvia made it clear she didn't like her bratty grandchildren from Nadine. Also that same episode where Nadine competed for the attention of Mr. Sheffield was due to the fact Sylvia always paid more attention to Fran growing up.
Okay, so C.C. and Niles marry as Fran is delivering her children because C.C. felt strange since Niles proposed. And guess what? It turns out C.C. is pregnant! Sure, it sounds dandy now, but we learn this after Fran's water breaks in the elevator and we briefly see C.C. drinking from a small bottle typically used for alcohol.