I find that children quickly learn that there is the "home way" of doing things and the "daycare way" I would let this little one cio with of course monitoring. She will quickly learn this is the way it is a dc. I wouldn't have a problem the sippy cup, though the breast feeding dcm's I have had as clients do their breast feeding before and after daycare and let the child drink water here if they don't want them to have milk.