add to
• be joined to something so as to increase its size, number, or amount.
• "this development added to the problems facing the staff"
Similar:
increase,
magnify,
amplify,
augment,
intensify,
heighten,
deepen,
enhance,
boost,
inflate,
escalate,
exacerbate,
aggravate,
inflame,
worsen,
make worse,
compound,
reinforce,
add fuel to the fire/flames,
fan the flames,
put salt on the wound,