Anything that is out all the time has to be safe or more or less safe for any age that I have in care since if my back is turned one way the babies will be into stuff in the other area. While they have their morning naps is when I would do "big kid" things with the others and usually at the table so that it is easier to find things that fall off the table when it is cleanup time as compared to the middle of the playroom.

You could try to gate off an area for either the babies to be or the big kids to have special activities.

As far as putting things away I try but kids get so excited they forget. I have things in area so as long as they are in the area they can make a mess there but must clean up the mess before moving to another area. So it is ok to have the blocks out and a few dinosaurs and the barn nearby but it all must go away if they want to leave that area to go to the playhouse or book corner. So it gives them the freedom to be creative within the confines of the space. Use shelves turned sideways, area carpets, etc. to define where one kind of play stops.