How about telling her straight out that she is a big girl and crying at your house is not allowed. Maybe let her pick a DVD to watch for 20 minutes right after drop off, tell her if she doesn't cry and is a big girl you will let her chose something.

I had a similar situation and my little dcg loved Dora so I let her watch it. I'm not sure of your morning routine but for me it's treehouse for the 1st 1/2 to 40 minutes until everyone is dropped off.