My immediate thought is that it often helps to start out by acknowledging the wanted thing:
"I know you want to go outside right now."
By acknowledging the wish, you are also acknowledging their feelings which is often the first step in moving past whatever it is they are stuck on - knowing they were understood. Then observe or question about the thing getting in the way:
"Do you see how dark it is outside?"
It often works to present this observation as a question that causes them to observe as well. Another example might be:
"but aren't you hungry? I think it makes sense to have dinner first"
Finish by asking about an alternative and then follow through on the
"In the morning, we will make sure you get some time to play outside
right after you have eaten your breakfast."
When you make "deals" like this, it is important to follow through or they will not continue to work - because your kids will eventually stop trusting you to follow through.
It is likely that if your child is perseverating, this won't end the conversation (especially at first) and you will need to answer the question again. However, by setting things up this way, you set yourself up to successfully become a broken record,
"Do you remember what I said last time you asked?"
"Do you remember what the deal we made was last time you asked?"
"What did you tell me we agreed on the last time you asked that
This prevents arguing about it at least and puts the responsibility on the shoulders of the child to start to remember the limitation, rather than on you having to restate the bummer thing over and over again - preventing fights and tantrums at least to some degree about things. You can also restate an acknowledgement of the child's wish before your question such as:
"I know you really want to go outside. That sounds like fun to me too
- but do you see how dark it is out there? What did we say could happen last time we talked about this?"
When you get tired of the whole broken record thing, you can also try impartial observation of your own recollections and feelings:
"I seem to remember answering this question before. . . Hmm what
was my answer?"
Or the frank and completely honest observation (which works well once they've reached attaining the theory of mind developmental step (you know they've broken through this barrier when they start trying to "trick" you, have attempted bald-faced lying, or are starting to fully understand jokes based on words with double meanings.
"I am starting to think you are (stuck on, perseverating about, . . .
said issue) this starts to be frustrating for me after awhile, what
can we do to move you past this (want, desire, wish, thing. . . )?
Many people will recommend redirection - which is another useful way to go - but with kids with a neurological reason to perseverate on things, I have found it can actually make them go after the thing they want that much more insistently and intensely. I really find that first step of acknowledging feelings to be incredibly helpful and the big key so that if you take that first step and then try re-direction you are more likely to have better luck with the redirection aspect of things.
When the problem is that your daughter is upset with a role-change in your routine, you can use the same procedure, but involve the other parent and go through the procedure preventatively. i.e.
You: "I know you are used to mommy doing this part of your routine."
Mommy: "I'm sorry I can't do that tonight, I am . . . tonight and
can't, but I love you and will look forward to getting back to our
usual way tomorrow night."
Then, when she brings it up in the moment, your question is,
"What did mommy say about why she can't do this with you right now?"
and "When will mommy get back to the usual routine with you?"
Kids that struggle with this kind of behavior in the extreme are really a challenge, but they are a challenge because routine means security to them in a way we can't relate to. When Dustin Hoffman got ready for his role in Rainman, he spent quite a bit of time at the ICA (Illinois Center for Autism) studying to prepare (and donated quite a sum of money to the center to boot). So, you can be sure his acting here isn't far from reality (plus I've worked with these kids and while he depicts a fairly extreme case of a high-functioning sevant autistic, It is fairly true to life in my experience as well). There is a reason for the movie's success and it has a lot to do with the heart and care Dustin Hoffman put into his role as far as I am concerned. Point is, as hard as it is, patience and empathy with low emotive tonality and action is the key in getting your message across.
Hopefully, as she gets older and hits some of those developmental milestones that are more emotionally related, things will get a little easier in this regard.