I feel this is a nice alternative and there is loads of uk and polish charities that support children overcoming abuse and also those who support children living in poverty.tbh if anyone wants to give money to something in her memory giving it to a child abuse charity would be better to help other kids. Another option would be to send a toy to some charity for a child for Christmas in her name
I do feel the original poster didn't mean any badness and just wanted to do something nice . The harrowing details of the case can leave an image of Sara being alone in life as well as in death and I suppose the suggestion of adding mementos to her resting place was an emotional response to wanting to show some form of love and care.
The information we are reading is focused on her life with the defendants a lonely and isolated existence and it is easy to forget she has a loving mother and other relatives who were deprived of a part in her life by animals. Sara's relatives are mourning and grieving and just want privacy to do that . So best to leave them be .This is the best way of showing we support them .