I've only been to DLR once, and then only for a few hours, but I'll offer what help I can. It looks like I'm in a similar situation to your daughter, in that I can walk, but need a chair outside the house (for me it's due to Fibro).
As DLR was built a fair while ago, the wheelchair access is often an after-thought, rather than being included into the design. For a lot of them, you will be directed to the exit, and will queue there with other wheelchair parties. Due to safety and evacuation restrictions, they can only have a certain amount of people with limited mobility in the ride at one time, so the line may look short, but take a long time to get through.
It looks like you've got a fair bit of information from the others already, but I'll just throw in what I can, on top of that. For Haunted Mansion, let them know she'd like to stay in the chair as long as possible, and you'll go through the stretching room and line in the chair, then it will be parked out of the way. When you get to the ride exit, you will stay in the car while everyone else unloads, and ride around to the loading area and her chair. Once you've both got out, and she's back in the chair, you will be directed back towards the stretching room, along a roped-off bit of the queue, so you don't need to fight through the oncoming hoards. You'll then ride up in the Stretching Room (now a shrinking room), and go on your merry way.
For Pirates, you join the line at the exit in New Orleans Square. When there is space for you to load, a CM will come and get you, and take you in through the exit path to the loading / unloading bay. You'll get on at the unloading side, ride through and then come right back to the chair at the end. One piece of advice, though: if she would find it hard to step over the side, onto the seat, and then down to the floor of the boat, make sure she doesn't wear a skirt! I've made this mistake twice (once at DLR, once at WDW), and it doesn't make for the most elegant of entrances to the boat
That's about all I can think of right now. The CMs are lovely, so if you have any problems, or don't know what to do, just ask one of them and they will give you a hand. If transfering into ride cars hurts or wears out your daughter, don't be embarrassed to use the accessible vehicles. I've done this on a few trips, as long as there wasn't a line of wheelchair users waiting, and it has made the difference between having to go back to the resort half way through the day, and having a full and fun day in the parks
Hope you have a wonderful trip!
