A friend of mine organised her own and had the RSVPs sent to her MIL as she was having it at her house. She organised the games herself and she had everything planned quite well. I think if you are the type of person who throws a great party no one is going to care or think it odd that you did it yourself anyway.

i think you should just tell her that you would be more comfortable doing it yourself, but delegate some menial jobs to her so she still feels like she is 'organising' something.