Mary Sciarrone (née Valastro) is the third-from-oldest of Buddy's sister. In the fifth season episode "Stained Glass & A Surprised Danny," she had to be taken out of the bakery for a while after she was accused of being mean to some of he employees. But she and Buddy eventually patched things up and Buddy rehired Mary as a cake consultant, returning to full-time work at the bakery in the episode "Silly Seuss & Surprise!".
Mary has two children who're fraternal twins: a son named Joseph Jr. and a daughter named Lucia. Mary's husband, Joseph "Joe" Sciarrone Sr., is the only one of Buddy's brothers-in-law to not work at the bakery--Joey's the head baker, Mauro is Buddy's current right-hand man, and Lisa's ex-husband, Remy, Buddy's former right hand man, also worked at the bakery.
According to Mary in the "Family Secrets" special, Joe already had a job back when they first met, so it's not like he needed a job--although Joe still helps with the bakery business itself, so even if he doesn't work there, he's still involved with it.