Try setting the cuffed player to his PlatformStand state. When a player is set to this, they can’t run(or move by itself) in any way and makes all of their body non-collidable except the humanoidrootpart.
if Target then
Using = true
RemoteEvent:FireClient(player,'Use')
local CuffedUser = TargetTorso.Parent
local CuffedUserHumanoid = CuffedUser:WaitForChild("Humanoid")
CuffedUserHumanoid.PlatformStand = true
weld = Instance.new("Weld")
weld.Part0 = PlayerTorso
weld.Part1 = TargetTorso
weld.C0 = CFrame.new(0,0,-3.5)
weld.Parent = PlayerTorso
end
of couse you have to make sure you disable PlatformStand when you let go of the player