Ok, I hear what everyone is saying about needing more days, but from what I understand, that is not in the cards right now. So with the time you have, here is my rough plan for you just off the top of my head. (We will be there for 3 days in October around the same time).
With the choices of Mon (Oct 30), Tues (Oct 31) and Wed (Nov1), I would pick Monday first. Reason: Tuesdays are typically EE days and since you won't have that option with your ticket, there will already be some lines when you get there at regular opening. You are planning on being there at rope drop, right? Otherwise, it will make if more difficult to get all you want done. Speaking of rope drop, something to keep in mind if you are traveling from a relative's house - LA traffic! Any chance you can get an inexpensive hotel across the street from DLR the night before?
OK, moving on. Let's assume you get there on Monday morning right at rope drop. You and kids can head to Fantasyland while Dad collects FP for one of your favorite FP enabled rides (i.e, Space Mountain - fast for DD, or Splash, Indy, etc). Next Dad returns to be with you and kids and rides in Fantasyland. When FP from Space or whatever you chose is ready, send Dad to pick up FP for next favorite ride. While Dad is at it, he can also get FP for Cartoon Spin (I believe that is the name) since it is not connected with the FP system and won't count against your FP return times for other rides (see Hydroguy's posts to get more info - very helpful).By the time he returns, you've spent approx 1-2 hours in Fantasyland, done all those rides and are ready to move on.
Where it you next favorite land? (Even if Fantasyland wasn't your favorite, I suggest you go there first since those ride don't have FP and lines will get long during day). Back to next favorite land. Generally, what I am aiming for is getting to non-FP enabled rides early before crowds arrive and collecting FP for more popular rides to be used later. At some point, you'll need lunch. Don't forget to send Dad for FP right before lunch, so the time to pick-up another one will be ticking away while you eat. Also, remember FP don't need to be used at the return time listed, just anytime after said time. (Again, read Hydroguy's posts on this for more info)
Others have said Fantasmic at DLR is better than MK. It is. However, I don't know the October schedule right off hand and don't know if it will be showing Monday night. If it is, you can try to catch it. However, if it is showing, then maybe that means the fireworks show will be going as well. From what I understand (I haven't see it yet) that one is not to be missed.
OK, let's assume Fantasmic and fireworks aren't scheduled during weekdays (a likely possibilty). There is the Halloween nights schduled at DCA as Hydroguy mentioned. Here's the thing. You can buy tickets (assuming they are still available) for that and have an opportunity to do a very brief visit to DCA after you have accomplished most of DL rides. I believe there will be trick or treating stations, meet and greets, as well as some rides open. DCA. I want to say the hours are 6-9 or 7-10 pm, but can't say for sure. During that time DCA will be closed to regular tickets and open only if you have the Halloween tickets, which might be a reasonable cost to you (I think 20-25 bucks per person) as opposed to staying another night in hotel and buying 2 day pass. I really don't know if this is indeed cost effective or an option, but just some things to think about.
I am now done with my ramblings, hope it gives you something to think about and look into. My best suggestion, read Hydroguy's posts - a trip report about DLR last August and comparing to WDW to DLR just recently in June. These will really help you conquer DLR! Good luck and have fun, no matter how many days you are there
Yes more days would make it easier to see more things, but you can still do a lot in one day and it is definetly better than none! Perhaps as a compromise on 2 days, your DH would be willing to do the Halloween party on the 31st at DCA stay over night at a neighborhood hotel, and do Disneyland on the 1st. This way you will get a taste of DCA, plus some Halloween fun, and be right next door to get an early morning start on DL.
