We ended up with ducks when I encountered two "free" ducks in a feed store in suburban St. Louis last summer. They had been "Easter ducklings" and then the family realized what full grown ducks do to a yard; I took them because I was afraid they would end up as someone's dinner. We threw up a quick temporary fence for them, and they spent nights in a playpen in the kitchen until we built them what we thought was a secure house. (Double walls and floor, with insulation, double paned windows, with wire reinforcement, next to our bedroom wall, for additional security.) We always plan our schedules so one of us is home before dusk, to secure the ducks and the chickens in their houses. Then, during a cold spell this winter, when we weren't letting them out, I went to check on them one evening and found Dumpling without a head and Dagwood with awful head and neck injuries. After researching feverishly on the internet, I concluded it had to have been a weasel. If I pulled really hard at the door (which is double latched), I could just barely stick my fingers under, up and in. Apparently, that is enough for a weasel. We immediately clad our chicken house in 1/2" hardware cloth to weasel proof it.
Dagwood was clinging to life so precariously that I was afraid to take him to the vet for a week - I thought the trip would likely kill him. Fortunately, I always keep a stock of antibiotics, anti inflammatories, and pain relievers for various species on hand. I put him in the bathtub 3-4 times a day, force fed him, and treated his injuries. At the end of a week, I thought he would survive a visit to the vet; the vet was amazed that he was alive, with the injuries he had. Well, we continued with that regimen for a couple of months, with Dagwood living in the pantry. He refused to start eating on his own; he had to be hand fed. He had limited mobility in his neck because of his injuries, and when he was strong enough, we decided to get hi a companion duck, in the hope that the companionship would help him emotionally and interacting physically would be good rehabilitation for him.
My SO mentioned it to a woman from work, and she had her brother hold back two females from a flock he was selling to a Chinese restaurant in Chicago. We had intended to only get one duck, but knowing their fate otherwise, we bought both girls. The introduction went well, and almost on a daily basis, we saw Dagwood regaining more and more mobility. Now, you would not be able to tell by looking at him that he had ever suffered trauma.
This summer, we built them a pond, to replace their kiddie pool. The absolute joy when they first went in the pond brought tears to my eyes.
They are extremely vulnerable to predators, so you really do have to plan your schedule to keep them secure at night - raccoons, foxes and other predators can climb even high fences, and there's no fence that can keep a weasel out.
My 13 year old daughter absolutely loves them though and badly wants one. I am considering allowing it when we move (next 6 months or so.)
Your daughter won't be sorry! 
