Hi Karen!
Thank you for visiting the Moms Panel!
You will find lifejackets are provided at both water parks. I am not sure if you can ride together down the single slides, but at both parks there is a family raft ride, that take at least 4 people so you can enjoy that together (I now scream more than more son on any of these rides!, but they are great fun for the family). There is also a lovely river to float around at both parks, that you could enjoy together, and that is perfectly fun and free of big drops and too much splashing.
Depending on your daughter's height, there is a safe play area at both parks for youngsters, with mini slides etc. but the height limit is 48 inches.
Have a visit to the
Typhoon Lagoon and
Blizzard Beach web pages to see which park would suit your family best. I am sure you will find plenty to enjoy, at both parks.
If you have any other questions, please come back and ask me - I would be happy to help you plan your magical vacation!