Would this conversation be different if I was, say, a concerned grandparent? A neighbor? Aunt? Uncle? Psychiatrist?????
Nope, it would really be the same. If it was a psychiatrist, they wouldn't be on a public board asking, they would be doing their duty by reporting it to the proper authorities if children were being neglected/abused. If it was a grandparent, aunt, uncle, neighbor, hairdresser, dog walker, ect, we would tell them NUNYA, as in none of your business, as well. Stepmoms aren't the only ones that know better than parents, others try to interfere as well, but stepmoms are the largest bunch.
Look. I know you mean well. I know that all of the neighbors mean well too. You care about these kids, we all realize that. But it isn't up to you to solve all the problems you have uncovered. It isn't up to you to "teach" your husband ANYTHING in regards to his children unless they are children you biologically share with him, then you can have at it.
There are a lot of kids I know that have parents I consider crappy. Do I interfere? No. Do I try to guide them in the parenting ways I consider appropriate? No. Do I try to TEACH them, as you are doing, how to parent? NO! And yes, I realize I am not married to them, however, my husband isn't perfect and I don't try to teach him how to be. It isn't my job to train an adult, or mold him into what I think he should be.
I've asked you before, and you haven't answered. Why is it up to you to try and solve all these issues? They functioned before you came along, even if it isn't in the way you would personally have functioned. So why is it up to you to point out how they are doing it wrong?