The original plan for Fuller House never intended Michelle to be a returning main character. The Full House spin-off had been in development for a while before it was picked up by Netflix and premiered in 2016. All of the main cast from the original sitcom reprised their role in the sequel sitcom except for Mary-Kate and Ashley Olsen, who alternately played the Tanners’ youngest daughter, Michelle, in Full House. The character’s absence loomed large over the five seasons of Fuller House, but as it turns out, even if the former child stars had agreed to appear, Michelle wasn’t set to be a regular player in the show.
Leading up to Fuller House’s debut, there was a lot of contradicting information about whether or not the Olsens were participating. In the end, both sisters maintained that they had no intention of revisiting their showbiz career, as they had long retired from the industry to focus on their current jobs as esteemed fashion designers. For the first few seasons, the spin-off attempted to make Michelle relevant by constantly referencing her and her supposed job in New York as a fashion mogul. This kept viewers hoping that eventually, one of the twins would change her mind and join the Netflix sitcom.
As it turns out, however, even if either Mary-Kate or Ashley agreed to appear (or both), Michelle wasn’t going to be a series regular on Fuller House. According to series creator Jeff Franklin [via THR] who also spearheaded Full House, he always knew that the Olsens were never going to regularly appear. So, early on, they decided that to mimic the original sitcom’s premise, Kimmy was going to be the third lead character joining DJ and Stephanie instead of the Tanners’ youngest sister.
“Obviously, I knew Michelle was not going to be a permanent character unless I recast the role and that was not something that I really was thinking about, so my hope was just that it’s great that we had Kimmy and we could bring her in and it would still be three women. My hope is that we would see Michelle from time to time as we see the other characters.”
Based on Franklin’s quote, if one of the Olsens did return for Fuller House, the best role that she’d have had is a guesting one. Kimmy was always positioned to take the third leading role after the two older Tanner kids. In hindsight, this made sense considering what the spin-off was trying to do. It’s no secret that the Netflix project was focused on recapturing the magic of Full House, essentially borrowing its premise. Since the original show’s leads included a non-blood relative in Joey, Kimmy as his contemporary was a better fit than Michelle would have been.
Assuming that the Olsens participated in Fuller House and the sitcom pushed through with their plans to essentially relegate her as a side character, it's curious what the response would be. Franklin had been open about the established fan community of Full House as their primary target market when shaping the story of its spin-off. Considering how central Michelle was in the original show, giving her a supporting role may not sit well with many of the classic sitcom's cult followers.