Not sure if 毎 can be used for people, but personally I would go more with
すべての子ども. I guess you learnt using romaji coz you used わ for the topic. Even tho in romaji it is written "wa" it uses the hiragana は (only case that I know of where は is read wa).
Another thing, I do this mistake alot too. Watch carefully when you type with IME the outcome. Some letters need to be pressed twice and some requires a ' to avoid melting together letters. When you typed みんな you pressed only once the N so you got みんあ.
So the way I would write it is:
すべての子どもたちはぽちぶくろがほしがっています。
Forgive my ignorance, but what is a ぽちぶくろ?
EDIT: Forgot to tell you that I am a student so errors hide everywhere in my Japanese phrases
