If you are ok with it try Monkfruit as a substitute for sugar. It has a more natural taste than stevia and you use the same quantities as if you were using sugar. Try making a basic sauce with Monkfruit, Lemon juice, cornstarch and water if you like lemon flavoured sauces and cook until it thickens. Alternatively add Monkfruit with a little bit of tomato ketchup, white or brown vinegar, some kecap manis, cornstarch and water (to your own taste) and cook until the ingredients start to thicken… Just play around with a few ingredients that the children might enjoy and go with that.