I have six spoiled house ducks and can help you and answer any questions you might have. It can be a little scary at first, but they are great pets indoors and out! Feel free to PM anytime!
I'm still working on it, but hopefully by April we'll have a whole section of duckling care for house bound ducks! I'm-a working on it!
The best thing to remember right off the bat is, if you want to keep a duck or two in the house (I recommend no less than two), you'll need to bond well to your ducks. If the are imprinted on humans this will be easier, but it is not impossible for a non human imprinted duck to love a human as well.
This will sound cruel, but after many tries myself, it is the best way- separate them into different brooders. We used big plastic containers. Separating them (but give them a mirror so they aren't too lonely, and stuffed animals and toys help too) makes them rely on you (or the person the duck is to belong to) and to bond to you. Picking the duckling up many many many times a day and holding them, petting them, getting them used to you fussing with their feet and wings and bill are all good exercises to practice (so if you ever have a problem they will be okay and calm while being examined). Let them lay with you and snuggle with you whenever you are just sitting down to watch TV. We used to drag their brooders all over the house so they were always with someone. We use to let them take supervised baths together, but that was the only time they saw each other until they were fully feathered. My two most bonded and well behaved ducks Victor and Ming Mei, were separated until they were 8 weeks old (they could see each other once they hit four weeks and could stand tall enough to see each other) and they were always kept in the same room. I even snuggled with both of them at times. And they took baths together, otherwise they were in their own houses. Once they were old enough, I build a 4x7ft indoor pen for them. The second two oldest, Vinny and Ollie I got when they were 8 months old (they were dumped on me and we took them in), took a long time for them to even trust us. Vinny is very sweet and tends to love everyone while Ollie only loves my boyfriend Joe (aka Duck_feeder, who you can also feel free to PM). They were put together at around 6 weeks old from what I was told. The youngest of our bunch, Moxy and Norie lived separate until they were about 4 weeks old and then were allowed to live together in a bigger brooder. They were not allowed to live with the older ducks until they were over 12 weeks old. Norie is similar to Vinny, loving just about everyone and Moxy is a lot like Ollie, loving only her dad.
Once they are bonded, keeping up with picking them up, hgging them, holding them, letting them hang out with you keeps the bond strong. My ducks live indoors in a big pen taking up a whole bedroom most of the time. We made it out of Ikea cabinet frames. When it's nice out, above 55 degrees and we can watch them (we got hawks in the city of Chicago) they get to go outside in our mini backyard to play if they want. Usually only 3-4 want to go on any given day. They always come inside for their baths and always sleep in their pen in their room (of course after getting their treats). We have all girls so we don't have to worry about babies, but we still get a broody snooty every now and then.