Cliff and Clair were talking about how many kids they have together. They were saying it's a good thing we only had 4 kids and not 5 kids. They do have 5 kids: Sondra, Denise, Theo, Vanessa, and Rudy. In other episodes, they say they do have 5 kids.

The Huxtables only had 4 kids in the pilot. After the series sold to NBC, they decided to give them an extra daughter to match Cosby’s real life family.

They should have stuck with 4. Sondra was boring and useless.

Their living room is different in the pilot too.

The Huxtables only had 4 kids in the pilot. After the series sold to NBC, they decided to give them an extra daughter to match Cosby’s real life family.

They should have stuck with 4. Sondra was boring and useless.

Why was the series sold to NBC and who owned the series before NBC?

Their living room is different in the pilot too.

Yes the living room was different. I liked the new look better.

Why was the series sold to NBC and who owned the series before NBC?

When they say "sold to NBC", they mean that NBC green lit the show, or allowed it to air.

The Huxtables only had 4 kids in the pilot. After the series sold to NBC, they decided to give them an extra daughter to match Cosby’s real life family.

They should have stuck with 4. Sondra was boring and useless.

Actually, the real reason that Sondra was added was because Bill Cosby wanted to show the effects of successfully raising a child, hence, a college graduate.