SofiaAmes - I am a little bit pissed off taken aback by your posts.
Where does it say in my post that I don't stick to her rules???? I have NEVER deliberately ignored them and I do absolutely everything I can to make sure I do as I am told.
Those 3 children have no health issues whatsoever and I would never do anything to deliberately endanger them. I buy in the food/drinks they are allowed, I use all "authorised" products (sun cream, baby wipes, soap etc) I stick to their bedtimes, yes they do sometimes watch more than 20 mins of CBBeebies but you know what, I have also become bloody brilliant at keeping them amused with games, making anything out of old toilet rolls and bits of card board and silver foil and DP does a good turn at all the voices when we read to them.
As for the supposed "impertinence" of my partner giving them treats - WTF!!!! Where does it say it was "candy"???? Those treats are buying them silly kids magazines (Peppa Pig etc), stickers, felt tips, allowing them to go on those stupid ride things you sometimes find outside of shops, letting them go on the roundabout at the park and just generally trying to get them to relax and enjoy being kids. Oh yes, here's one you can shoot me over - the odd non-organic strawberry 
with a tiny (less than 1/2 a teaspoon over 500g of stawbs) bit of sugar . Perhaps sneak was a bad word to use, BUT we have certainly never or would ever say to them "Don't tell mummy"
If you had read my OP correctly, I was actually surprised at her reaction to the kids seeing a Carry On film. I was completely UNAWARE she classed them as adult. That was my actual question, did any other mother feel that they were classed as adult films???
I didn't sit them down to watch the film, DP had the film on whilst he was doing something to the fish tank. I knew she was due to come and collect them and she likes to find them calm when she calls, so I got them to sit down with their ice lollies, whilst I packed up their stuff. They started giggling at Jim Dale coming down the stairs on a trolley and because they were being so cute, I naively left them watching the film with DP.
AND just for record, I am being drip fed rules - when I had them at the beginning of the week I had fed the youngest too much banana, the time before that I gave them jam sandwiches, which contained both spread and jam - and was told that she didn't want them having both, spread is for savory only. That's not ignoring them. That's me being unaware that she doesn't like that, so another 2 rules to add to the growing list - and yes, I do find that exhausting. Could anyone honestly say they wouldn't????
I am sorry your child has health issues and your friend was unable to comply with the rules that made him ill. I would rather harm myself than do anything to harm those children. She is their mother and what she says goes. If she told me they could only eat marmite on toast, then I'd probably think she had gone mad, but that's what I would feed them & nothing else.
To everyone else - thank you for your posts 
I could tell her feck off but I love those children and her, even though she can be a nutter at times. She has been an exceptionally good friend to me and I know she would drop everything in a heart beat if I needed her. BUT I am going to have to speak to her about the constant add on rules - I have been trying to put it off, but it appears it's going to have to be done.
P.S apologies for the long post, but I have OD'd on mini eggs and vino! Oops, naughty!!