Whoa.

Blossom's older brother and a former Nancy Drew will topline the upcoming ABC Family original movie "The Rules of Engagement." Production is set to begin in March and, given speedy ABC Family turnaround times, it'll premiere in June.

Joseph Lawrence ("Blossom," "Run of the House") and Maggie Lawson ("Nancy Drew," "It's All Relative") play a couple who become engaged after a year and a half of dating. They're planning a fun and off-beat wedding until her mother ("Taxi" and "Evening Shade" star Marilu Henner) throws a wrench in the works by telling them about the "rules of engagement" (whatever those are).

Soon their engagement is in shambles and their wedding is in jeopardy. Will they fall victim to the rules?

The telefilm will be shot in Toronto.

"The Rules of Engagement" was written by Alan Marc Levy and TV vet Steve Robman ("The O.C.," "Gilmore Girls") will direct with Joel Rice ("I Want to Marry Ryan Banks") executive producing.