I tend to re-unwrap objects a lot during my workflow / experimentation.
Whenever I add a new object with the same texture, I like to make the texture match the scale of it's siblings, so I unwrap all objects with the same material then scale the textures accordingly.
For example - Making a wood grain follow the length of an object instead of its height.
Unfortunately, whenever I do this, I have to re-rotate the faces of previous siblings.
Is there a way to make the faces stay rotated, so when I unwrap it again the faces stay in the desired orientation?