Meanwhile, Chord Overstreet's option as a series regular has not been picked up, meaning Sam may not be back to McKinley High on a regular basis.
The Hollywood Reporter has confirmed that Shum and Criss have been upgraded to full-time regulars, as first reported by TVLine, where they join the likes of Chris Colfer (Kurt), Lea Michele (Rachel) and Cory Monteith (Finn), among others.
Criss told THR early Friday from Ireland that the cast was preparing for their final concert dates and hadn't been talking much about the show itself, which recently added six new writers to its staff.
"I have no idea what to expect in Season 3, but I think it's going to be nothing but positives," he said.
The additions -- and possible permanent departure -- come two weeks after series co-creator Ryan Murphy laid out graduation plans for what could be most of the regular cast.
Criss was first rumored to be joining the series as a regular in November after he made headlines in his first episode singing "Teenage Dream." The single has since gone on to become "Glee"'s top performer on iTunes.
– The Hollywood Reporter