@Igfdyjxzyjkv
I asked if you had dc and what ages as often people without dc or who's own children are now adults forget what dc of ops child's age and stage are like I've seen that a lot. They expect young children to behave in ways they aren't yet capable of.
Entirely your choice whether to answer or not but that was the point I was making
It doesn't necessarily need to be a "fight" or even a confrontation, but it IS ops home and child and so she does have the right to have a say indeed the final say. What "power" do the in laws have here aside that bestowed by op and dh?
As far as they are concerned they rule the roost
But it's not their roost!
Nor did I at any time say op SHOULD "throw a tantrum" -
STOP putting words in my mouth!
I said raise the issue in a diplomatic and assertive way this is entirely possible to do.
I lost patience with my mum that time admittedly but when I had similar difficulties with my parents or other guests I generally managed to address it without it becoming an argument or even a heated discussion.
or let herself get emotional
Nice bit of misogyny there
Because god forbid a woman disagree with how she is being treated in her own home lest she be thought  emotional
Re routines - I did not say that every child that needs a routine adhered to has or could have a disability I was very clear about that, that was just possibly the case with my own dd. I have cared for literally hundreds of babies and toddlers over the years and some need a routine, some aren't fussed at all, most fall somewhere in the middle.
NOT just because of disability but simply personality differences. Children are as varied as adults in that. I'm on another thread totally different subject and one poster has a username indicating they're more of a lark, I'm most definitely a night owl, some adults like to always eat at a regular time (like these in laws - they don't want their routine disrupted but expect a child's to be!) others eat whenever...
If they are looking for basic respect - they need to start by GIVING it
I think you're just being deliberately inflammatory!
A definite possibility
Giving in to unreasonable demands in your own house will invariably lead to even more unreasonable demands
Totally agree
some kids just need less sleep
Also true!
Dd didn't sleep right through until she started school and even then was up at 5-30-6am most mornings - then teens hit and couldn't get her OUT of bed 
but people seem to forget there's such a thing as being a good guest too.
Absolutely!
That's reminded me - when I had flare up with mum at one point she went "I'd never behave like that" at which point dad reminded her of HER mil first visit just after my brother was born (prior to that we lived in same street!) mum was dealing with a colicky baby, a toddler and dad was on deployment. Her mil/my gran had supposedly come to "help" and caused ructions apparently with trying to correct EVERYTHING mum was doing with us. She lasted exactly 2 days before she blasted her with "actually help or go home! So far you've been nothing but a hindrance!"
Now I loved my gran...but she could be a bit much and quite...brusque/abrupt - even for a weegie! So I can well imagine how those 2 days had been!
Gran to her credit apologised and basically wound her neck in and was super helpful after that.
It was a turning point for mum and grans relationship and they got on famously after that. I'm told this is when my mum started calling her "mum" I don't remember it but I remember the relationship they had around me growing up and my mum was one of the few people that could get away with telling my gran to quit being so critical! Even her own dds my aunts didn't get away with that! To the point mum used to get phone calls from her sil's "can you have a word with mum? She's driving me nuts!" 
I suspect you are a MIL
Yes I considered that - likely to sons too
@Biscuitmonster2318 so sorry for your losses
I don't think anyone is saying pil aren't entitled to an opinion but there's a right and a wrong way to express it and sometimes it doesn't need expressing at all just think it!
My own now ex mil was lovely and super helpful. She very rarely if ever criticised but would express things as in "it was different in my day we did it x way" or at most "can I make a suggestion?" And then she'd explain a way of doing things and her reasoning behind it ex fil was a quiet man and not inclined to offering anything unless asked - but when he was asked he often had great ideas but he was very much NOT of his generation (he's in his 90's now) because he was raised differently to most as he was unfortunately raised in care.
Gotta go for now