Help with recreating the Roblox Dragger object.

I'm recreating the dragger object to seamlessly work with code that uses it already, all is well except I can't quite figure out that actual part dragging.

Basically I need to come up with a function that can take a table of parts, an offset point (the point grabbed at), and a new CFrame (that being mouse.hit). How might I do that? Also how would i get parts to stick to the side of other parts instead of popping on top?

My code so far (in a module script):

local Dragger = {
    MainPart = nil,
    GrabPoint = Vector3.new(),
    Parts = {},
    IsDown = false,
    MoveParts = (function(self, Parts, Offset, New)
        -- Here's where i'm stuck
    end),
    MouseDown = (function(self, MousePart, PointOnMousePart, Parts)
        print("Down")
        if self.IsDown == false then
            --set MainPart, GrabPoint, and Parts, Set IsDown to true.
            self.MainPart = MousePart
            self.GrabPoint = PointOnMousePart
            self.Parts = Parts
            self.IsDown = true
        else
            pcall(error("MouseDown is in use, call MouseUp before using again"))
        end
    end),
    MouseMove = (function(self,MouseRay)
        print("Move")
        if self.IsDown == true then
            --Move GrabPoint and Parts relative to GrabPoint
            local NewRay = Ray.new(MouseRay.Origin, MouseRay.Direction * 999)
            local RayPart, RayHit = Workspace:FindPartOnRayWithIgnoreList(NewRay, self.Parts)
            if RayPart then
                print(self.GrabPoint)
                self:MoveParts(self.Parts, CFrame.new(self.GrabPoint), CFrame.new(RayHit))
            end
        else
            error("MouseMoved called without MouseDown")
        end
    end),
    MouseUp = (function(self)
        print("Up")
        --stop the dragging action, clear mainpart, grabpoint, parts, Set IsDown to false.
        if self.IsDown == true then
            self.MainPart = nil
            self.GrabPoint = Vector3.new()
            self.Parts = {}
            self.IsDown = false
        else
            error("MouseUp called before MouseDown")
        end
    end),
    AxisRotate = (function(self, Axis)
        --Rotate on the given axis
        if Axis == 0 or Axis == Enum.Axis.X or (type(Axis) == "string" and Axis:lower() == "x")then
            Axis = CFrame.Angles(90,0,0)
        elseif Axis == 1 or Axis == Enum.Axis.Y or (type(Axis) == "string" and Axis:lower() == "y") then
            Axis = CFrame.Angles(0,90,0)
        elseif Axis == 2 or Axis == Enum.Axis.Z or (type(Axis) == "string" and Axis:lower() == "z") then
            Axis = CFrame.Angles(0,0,90)
        --[[else
            Axis = CFrame.Angles(0,0,0)--]]
        end
        print(Axis)
        self:MoveParts(self.Parts, CFrame.new(self.GrabPoint), CFrame.new(self.GrabPoint) * Axis)
    end)
}

return Dragger