A.
Hi D.!
This is A. and our family lives in Knollwood in Granger. We have two boys ages 4 & 22 months. I wanted to try and think of ideas for what I remembered in your question was 20 little girls.
I am thinking of some places (just ideas).. The Little Gym, they have birthday parties and been to several there..very fun for the kids,..they do all the work, located in Mishawaka. I am sure you know about it. Also you could have a b-day party at the really nice Bowling Alley on Douglas behind Steak & Shake (Strikes & Spares).. kids love to bowl, especially for that many little girls. Another idea is to have it at your home and rent (this is what I did when our son turned 4) was rented a Moon Bounce from House of Bounce. I ordered 5 large pizzas, then had cake and I did the icecream cups (less mess) then the kids went outside and jumped for an hour or so, then they came inside for presents, then they all wanted to go back outside to jump some more. It was a big hit!
My neighbor across the street last year did a theme of a Tea Party because her little girl turned 5...but personally I think that's too much work for that many children. I hope these ideas help. Feel free to contact me at my email address. Good luck! A.