RadarOnline reports that a 'high level source' at Fox has revealed that Monteith's real-life girlfriend Lea Michele and series co-creator Ryan Murphy "intensely dislike Dianna and have both worked to marginalize her as much as possible."
The insider added: "It's shocking, because even though she's not contracted for this season, many other actors returned to pay tribute to Cory... even ones with less of a story connection to Finn than Dianna had!"
The source went on to explain that Lea and Murphy "never saw her [Agron] as a team player" and that they "simply did not want her sharing the glory for this very special episode."
Monteith was found dead at age 31 in a Canadian hotel room after succumbing to a fatal combination of alcohol and heroin.
The talented singer and actor had battled substance abuse problems before and had gone to rehab to address his addiction.
Show creator Murphy recently told The Hollywood Reporter that performances in the upcoming episode were raw and heartfelt for the late actor.
"Almost everything in that episode is from the first take of every performance because the actors and the crew had a really hard time shooting it," Murphy said.
"I've never seen a crew that you can't continue shooting because they've left the room sobbing. It was very hard. I struggled even working on it because what you're seeing is what they felt not just about Finn but Cory," he added.
The Quarterback episode will air in the US on Thursday at 9pm on Fox.
MailOnline has contacted both Ryan Murphy and Dianna Agron's representatives for comment but have yet to receive a response from either party.
- DailyMail
