Can two blended families coordinate a parenting schedule when both parents have new partners with children?

Yes, and this is a common situation many parenting plans are written to accommodate - the underlying legal schedule still belongs to the two legal parents of the child in question, but that schedule can be designed with real flexibility so it works alongside each parent's own blended household, including any stepsiblings from a new partner's children. A workable plan often builds in some predictability, like consistent transition days, while leaving room for each household to manage its own internal logistics with a new partner's children.

Coordinating two full blended households well usually comes down to communication rather than an increasingly detailed written schedule - trying to legislate every interaction between all the children involved in a formal parenting plan tends to create rigidity that doesn't hold up well to real life. Many families find it useful to build in a regular check-in, whether informally or through a co-parenting app, to handle scheduling conflicts as they arise, alongside a core written schedule that covers the essentials clearly. A family mediator experienced with blended families can help design a plan that's detailed enough to be useful without being unworkable.