He already said: "I put 3 pieces in each bag" - so, now one kid who notices he only has 2 gets upset ( as little kids ALWAYS DO) - and when the mom seeks an easy solution to the disparity
An easy solution is not always the best. Yes kids will get upset . It's a parent's job to tell them it's rude to ask for more.....or get upset about the amount of free stuff you've been given.
Just my analysis.