LibertyBig Boy's Denim Bib Overall, Rigid Blue, 12

What size overalls will fit a 12 year old that's 86.6 pounds at 4'58 in tall?

I'm 5'6 ,130 lbs. will the 16 fit

Niece wears girls 14-16 and another one wesrs women's 4. What size bibs should I order?

If I'm 5.1, and 125 lbs, is size 18 or 20 better?