This seems quite simple to me.
If you don't like the level of 'help' you're getting, then pretend they haven't done the dishes, make it your DH's chore... his chore will be quicker (cleaner dirty dishes) your helpers feel like they're helping, the dishes still get done. OR do the dishes before they arrive.
Being very harsh, you did the crime, you do the time (had babies) no one said it would be easy, 'help' in any form is a bonus, even if it's unhelpful and annoying.
YANBU to find it irritating, but YWBU to complain too strongly.
I suspect a strong routine is called for, so that eventually the helpers have nothing to do at all!
Being slightly more fair, I was totally useless with anything other than 'baby' in the first few months of both my childs' lives, and DH dealt with all other aspects of life, not to my standards, but he did it and I won't complain. My mother's help is rarely helpful either. Do invest in a dishwasher, they're fabbo. Then you can rely on 'help' to stack it incorrectly, and put it away in completely illogical order. 