you may want to try a technique called that I use my trainer told me it is called dominant massage.
you start by laying the dog down on its side and have it put its head down and then proceed to touch ( massage) it don’t allow the dog to get up untill you let it once the dog gets us to this try it with the child near by and then on your lap work up to having the child touch the dog as well.
I learned this as a child with our other dogs and when we got a pitty I did what i know works when we took him to dog classes the trainer asked us to practice dominant massage which is basically what i had been doing. now he will come over and lay down and wait. often my two daughters will join in now i see them climbing all over him or laying down without any concern.
hope this works or that someone else has a tip that helps