Filming is well underway for That '90s Show, the sequel series in development at Netflix that serves as a follow-up to That '70s Show. Returning from the original series to help lead the cast are Kurtwood Smith and Debra Jo Rupp, with the two coming back as Red and Kitty Forman. This time, they'll be joined by their granddaughter as the married couple will have to look after a new generation of youngsters in an all-new decade.On Twitter, Smith took a moment to pay tribute to Rupp in honor of her 71st birthday. He not only names Rupp as one of today's most outstanding performers but specifically names his That '90s Show co-star as his favorite acting partner. With this in mind, we can only presume it didn't take too much convincing for Smith to get on board if Rupp was also coming along.

In the tweet, Smith says, "A very Happy Birthday to my favorite acting partner and one of the best actors working today. Debra Jo! I hope you had a wonderful day today!"

Of course, fans will know that Smith and Rupp have co-starred as the Formans on That '70s Show from 1998-2006. After 200 episodes, the pair had forever established Red and Kitty as one of television's most popular on-screen couples of all time, making their return a huge sell for the Netflix sequel series. Smith and Rupp previously reunited on Netflix for The Ranch, which stars their former co-star Ashton Kutcher and formerly featured Danny Masterson.

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The Carsey-Werner Company

Kurtwood Smith and Debra Jo Rupp are the only confirmed cast members from That '70s Show to appear on That '90s Show. Even so, it seems more likely than not we will see some of the other cast members from the original series making special appearances. There are rumors of other cast members like Topher Grace, Laura Prepon, Ashton Kutcher, and Mila Kunis speaking with Netflix about possible cameos. There's always the possibility of bringing in other recurring characters from the parent series as well, such as fan-favorite Tommy Chong as Leo.

The logline for That '90s Show reads: "Hello, Wisconsin! It’s 1995 and Leia Forman, daughter of Eric and Donna, is visiting her grandparents for the summer, where she bonds with a new generation of Point Place kids under the watchful eye of Kitty and the stern glare of Red. Sex, drugs and rock ’n roll never dies, it just changes clothes."

Leading the new cast as the Formans' granddaughter Leia is Callie Haverda. The show also stars Ashley Aufderheide, Mace Coronel, Maxwell Acee Donovan, Reyn Doi, and Sam Morelos. Along with reprising their roles as the Formans, Smith and Rupp are execuitive producing with Marcy Carsey and Tom Werner of The Carsey-Werner Company. The show is created by showrunner Gregg Mettler and writers Bonnie Turner, Terry Turner, and Lindsey Turner, all of whom are also executive producing.

That '90s Show doesn't yet have an official premiere date on Netflix.