In-laws are always late to events at our home. Looking for advice 🤍

My in-laws are about 40 minutes- 1HR late for birthday party’s for our children. They never notify us when they are running behind, so it can be super frustrating. We like to run on a timeline and it ends being dragged out because we are waiting on them. Them meaning his parents and sisters. What would be a good way without rubbing them the wrong way to ask them about this? Or should I just let it go and just continue with the party timeline without them?