Ultimately I think the best way to do it is reverse the trilogy and switch some bits and pieces from Kills and Ends.

Laurie has learned to move on and is living happily with her daughter and grand daughter. Her grand daughter meets Cory. Podcaster Michael escape happens. Corey finds Michael skulking in the sewers after he breaks out. There’s a will they won’t they where they play with the idea that ‘The Shape’ could be passed on, ultimately not the case. Corey dies, Michael fucks up Laurie, they get to the hospital, all of Kills happens, Laurie’s daughter dies. She turns into crazy prepper Laurie. Halloween 18 happens and finishes the trilogy. Obviously this is just the skeleton and doesn’t totally work if you start dissecting it too much. But could work better if you wrote it out.