How do I make it so this only effects one part in the model individually?

I made a snowballs game where you cannot get touched by the snowballs. When the snowballs touch a certain wall, they re-spawn and go to the top. The script works, but it makes ALL the snowballs go to the top, without letting them individually teleport to the top. What do i do? Also how do i make it so only the balls will reset them self, not if a humanoid touches the wall

local respawner = script.Parent
local start = script.Parent.Parent.Startpart
local model = script.Parent.Parent.Parent.SnowBalls
local children = model:GetChildren()

respawner.Touched:Connect(function(hit)
	for i = 1, #children do
		local child = children[i]
		if child:IsA"Part" then
			child.Position = start.Position
		end
	end
end)