all my dc have previously used m&s kids thermals as the cotton and lack of buttons ment they didnt irritate.
thermals are a must even on fairly mild days they sadly are no longer small enough to fit into kids sizes and m&s adult male sizes are a different fabric more like shiney thick tights and all have fly's or buttons.
thermals must be either cotton or simmerler or have a brushed fleece type of inside with no buttons or fly so they have to be pulled down to pee kinda like pj bottoms but not as baggy.
cost is kinda an issue as i need to get 8 pairs for each dc so a fair few all in one hit.
you were so helpfull with finding the perfect toothpaste i figured i would give you a try with this as well in the vague hope that my asd kids arnt the only ones who need thermals and have very perticular likes and dislikes