'Glee' SPOILERS: Season 4 Finale Debuts New Cast Members Patty Duke & Meredith Baxter and a Marriage Proposal

'Gleeks': prepare to "Gleek out" over some major season 4 spoiler alerts for the finale episode of Glee, premiering on FOX May 9th!

Newcomers to the Glee family, actresses Patty Duke and Meredith Baxter, will make their Glee debut during this season's finale. The two ladies recently signed on to join the cast of the hit TV show as a "longtime firmly committed lesbian couple who have been together for 25 years", confirms a source to E! News.

Even bigger than the news of the inauguration of the Oscar-winning actress Duke & Family Ties star Baxter into the Glee cast during the May 8th episode is the spoiler that there will also be a marriage proposal! No, unfortunately Finn is not proposing to Rachel again, but "Klaine" fans will be pleased and shocked to learn that Blaine will apparently be popping the question to his "on-again off-again" boyfriend Kurt, as Glee tackles the topic of same-sex marriage.

E! News reveals that during the final episode of season 4, Blaine will go into a jewelry store to buy a ring for Kurt, where he will become introduced to Duke's new character, the jewelry salesperson. She will speak to Blaine about his love for Kurt, and then she and her longtime girlfriend (Baxter) will offer to become Klaine's "mentors."  Patty & Meredith's characters will explain to Kurt and Blaine how hard it used to be for LGBT couples back in the day, and how much better it is for the new generation.

The inspiration for this storyline was the recent Supreme Court case regarding same-sex marriages, and one Glee source describes the storyline is "topical and sweet," reveals E!.

Gleeks will first meet Duke and Baxter in the season finale, which will be filmed next week, but both actresses will also be returning next season as recurring characters. Sources say the two were the first choice for these roles and immediately said yes.

Will Kurt be as quick to say "yes" to Blaine's proposal or will producers leave us guessing until the season 5 premiere?

According to the Twitter page of Lea Michele, who plays Rachel Berry on FOX's series, a cliffhanger ending is looking like a definite possibility. She tweeted on April 9: "Just finished reading the final script of #Glee for this season! So many shockers and huge cliffhangers!"

As HollywoodLife notes, one thing that is for certain about the final episodes of Glee this season is that Finn will not appear in the last two episodes, due to Cory Monteith's rehab stay for substance abuse treatment.

As for what's in store for the next season of Glee, co-creator of the show Ryan Murphy revealed that they plan to do "something that we've never done before" for season five. Any ideas of what that could be?

While we wait in anticipation, be sure to watch the final four episodes of the season on Fox's Thursday nights.