Who's the boss? had a couple
Sea 1
Angela's Ex pt 1 & 2: Angela's husband shows up with divorce papers that angela sent him.

Sea 4
Another single parent: Tony's new friend Kelly has stolen her child away fr the childs dad.

On Good Times, Wilona obtained custody and adopted Penny, an abused child.
Mike and Gloria Stivic separated and later divorced on All In The Family.
Lionel and Jenny Jefferson separated and divorced on The Jeffersons.

On Punky Brewster, Henry was battling this arrogant, grimy, money-hungry attorney named Ron Chillings after Chillings claimed that Henry was unfit for parenthood.

Archie Bunker's Place did

Wouldn't the two part episode "Adoption" from Diff'rent Strokes count as well?

on Will and Grace ... the episode that has to do with Jack finding out he is a father to Eliot and his mother wont let him see his father.. with Rosie O Donnell

the whole Ben birth thing on Friends..luckily everyone got along

Hmm well Ross has been divorced 3 times pick one lol

Damn forgot to add the episode of growing pains where the kids found out that Jason & Maggie almost got divorced.

Golden Girls - Dorothy and Stan's relationship throughout the show.