To ameliorate is to step in and make a bad situation better. You could try introducing a second lollipop to ameliorate a battle between two toddlers over a single lollipop.
The verb ameliorate comes from the Latin word meliorare, meaning “improve.” Food drives can ameliorate hunger. An air conditioner can ameliorate the discomfort of a stiflingly hot summer day. A sympathy card can ameliorate grief. Family therapy can ameliorate severe sibling rivalry. Anything that can lift a burden or make something better can ameliorate.