InstaWeld with Unions?

How can I make this work for Unions so not only parts will be welded?

local prev 
local parts = script.Parent:GetChildren() 
for i = 1,#parts do 
    if (parts[i].className == "Part") then 
        if parts[i].Name ~= "Part" then
        if (prev ~= nil)then 
            local weld = Instance.new("Weld") 
            weld.Part0 = prev 
            weld.Part1 = parts[i] 
            weld.C0 = prev.CFrame:inverse() 
            weld.C1 = parts[i].CFrame:inverse() 
            weld.Parent = prev
        end 
        prev = parts[i] 
        end
    end 
end
for i = 1,#parts do 
    if (parts[i].className == "Part") then 
        if parts[i].Name == "Left Leg" or parts[i].Name == "Right Leg" then
            parts[i].CanCollide = true
        end
        if parts[i].Name ~= "Part" then
                parts[i].Anchored = false 
                end
    end
end