You hide it! You pack it up, stick it in a lock up/parent's garage/friend's garage. At least, that is what people I know do. You streamline obvs, but when you have children, you hide most of their belongings and make some tasteful displays suggesting little tykes just ran off after very contained and tidy play, which magically happens when you buy this house, especially as a couple wanting to start a family.
They will find the odd teddy in weird places charming, whilst the owner apologises for the (curated) chaos. This does not in any way deal with the lock up of shite needing sorted. However a stand by name list may be useful.