Yours is a problem that plagues parents all over the world. Children tend to be messy and to resist any efforts at change along those lines. It sounds as though you are handling it wisely—taking away toys they do not put away. Perhaps you haven't kept them put away long enough? Just doing something once or twice does not always result in a change in behavior with young children. Also, you might tell them they cannot have friends in to play unless they put their toys away. The 4Â½-year-old may be a help: talk to her about how you need her help in teaching her little sister how to care for toys. Finally, I would suggest that you put away most of their toys and get out a few every week. They could help you decide which ones they want to play with each week.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.