Group for Physics

local mt = {}
function mt.__newindex(t, key, value)
    if key == 'x' or key == 'y' then
        for i = 1, t.numChildren do
            if not t[i]['_' .. key] then
                t[i]['_' .. key] = t[i][key]
            end
            t[i][key] = t[i]['_' .. key] + value
        end
    end
    t[key] = value
end
frontgroup.x = nil
frontgroup.y = nil
setmetatable(frontgroup, mt)