I've no idea how Substance Painter is likely to need it, but this shows the seams I added in wireframe view
[![enter image description here][1]][1]
And this shows the result after unwrapping again
[![enter image description here][2]][2]

Here is the resulting Blend file <img src="https://blend-exchange.com/embedImage.png?bid=L8aBs0Vb" />](https://blend-exchange.com/b/L8aBs0Vb/.


  [1]: https://i.sstatic.net/ZyX7w.jpg
  [2]: https://i.sstatic.net/umnWB.jpg