'The Big Bang Theory' season 10 cast news, spoilers: Katey Sagal & Jack McBrayer confirmed to guest star as Penny's family, Mary and Alfred's hookup cliffhanger to be resolved?

Penny's (Kaley Cuoco) mother and brother will finally be introduced when "The Big Bang Theory" returns for its landmark season 10 this Fall.
With Leonard and Penny's formal wedding coming up, viewers have been wanting to see more of her family members who she usually mentions in the show. During the 2016 San Diego Comic Con, it was revealed that "Son's of Anarchy" star Katey Sagal and "30 Rock" alum Jack McBrayer will join the cast as members of Penny's family.
Veteran TV actress Sagal has been cast as Penny's mother Susan and she will be introduced in the season 10 premiere. "Katey has played Kaley's mom before on 8 Simple Rules, and she told us she's always up for playing Kaley's mom," showrunner Steve Molaro said (via The Hollywood Reporter). Susan is described to be "stressed out" after years of living with her troubled son.
McBrayer, who is also set to appear in the premiere, portrays Penny's brother Randall. He has been referenced multiple times all throughout the series and he is known as an ex-convict who worked in a meth lab.
As far as the plot goes, Leonard and Penny's wedding may be one of the season's highlights. Raj will find himself in the middle of a love triangle while Howard and Bernadette prepare for the birth of their first child. Sheldon will probably have to deal with Leonard finally moving in with Penny, but it remains to be seen if he will get a new roommate to accompany him.
Season 9 left off with a major cliffhanger featuring Sheldon's conservative Catholic mother Mary and Leonard's newly-divorced father Alfred. The final moments of the finale saw the two characters ending the day and entering the same hotel room, leading many viewers to assume they hooked up.
Catch the season 10 premiere of "The Big Bang Theory" on Monday, Sept. 19 at 8 p.m. ET on CBS.