https://screenrant.com/fuller-house-michelle-olsens-return-jodie-sweetin-answer/

Stephanie actress Jodie Sweetin has the perfect explanation as to why Mary-Kate and Ashley Olsen didn't return as Fuller House's Michelle.

One thing that isn't acknowledged is the fact that the girls continued to be in front of the camera even after Full House ended. I believe that going forward down such a road only got to be tiring for them since they had been on it ever since the beginning of their lives. If a normal life is what they began to want, I can't blame them.

God bless you and the girls always!!!

Holly (a day one fan of them)