What I usually do is first to insist on the parents saying goodbye. I find the child struggles more if they leave when their child is not watching them. Also distract them with an activity or toy. Ask parents to bring in a comfort item or even a picture of themselves or the family. Something that is familiar to the child. Try to engage the crying child within a group of children; this will help the child to settle into the room whilst also starting to form friendships. Encourage the parents to call later to check on their child or tell them that you will call them.