Around a year after the events of the film, Alma Madrigal ( the Abuela) starts to notice her son Bruno has been avoiding the family again, so she does what she should've done all those years ago, and checks up on him. ( pure family bonding/ reconciliation; also slight extension of the scene where he finds them on his horse).
Taking place during the argument between Alma and Mirabel, but what if instead of simply remaining firm on blaming Mirabel for the miracle fading she actually tried to understand the pain she ( unintentionally) caused her? This leads her not only to realizing her mistakes, but to be willing to do whatever she must ( even if it means risking her own life to save Mirabel.)
Set about 2 years after the film, Isabella is still rather infuriated of Alma's actions regarding the mistreatment of her younger sister, and finally tells it like it is to her. P.S. Story does end well.
Around a year after the events of the film, Alma Madrigal has a nightmarish vision about the Casita falling, and everyone turning on her... through this, she begins to realize how important Mirabel truly is to the family, and Encanto and as a result learns to be better for her and everyone else.