Thank you for the information. I hadn’t looked fully at the tags yet. When I update the school I will add the correct tags following the mentioned guide.
You mention adding info to https://www.openstreetmap.org/way/293868620. Non of the schools in this area seem to have that set up so I will start doing that for them once this one is concluded.
My main question was regarding what to do with the (old school building). Because It isn’t disused and deleting the buildingand expanding the other building isn’t usually the best way about it.
Having read https://help.openstreetmap.org/questions/68593/transform-two-buildings-to-a-single-with-two-parts. Would it be better to create a new bounding box for the building and adding building:part=*. with * being either yes or Infant/Junior to represent yeach part of the school. That way it gets to keep the history, but represent the current use.