You don't say how old your daughter is but it sounds like a lovely theme for a party and you don't need a bouncy castle at all. You can buy cheap tiara sets from toy shops-ask your guests to come in prince/princess costumes, maybe do some activities like decorating paper crowns or you could photocopy an outline of a Disney type castle and give them glitter/glue/pens to colour it in (you could do that in the garden if you want to avoid mess). If they are aged 6+ what about getting some nail art kits- my daughter's friends loved doing that and they sat quietly whilst I stuck on the little glittery stickers and gave them a quick coat of clear vrnish to keep them on. Or you could do princess makeup with a little body glitter and pink eyeshadow. Cakes decorated with silver/pink sprinkles-plastic goblets to #drink from-if you get a bouncy castle it will just turn into bedlam. You can buy Disney princes songs CD and have a dancing competetitiom. And of course if they want a bit of quiet time you could put on Shrek or Cinderella for 10 mins.