Stacking multiple night.

[Anthonyexmouth]

If I'm stacking images from multiple nights with different flats do I stack them separately and then integrate the stack of stacked images. 

[Budgie1]

If you're using DSS then at the bottom of lower window, where the image list appears, you can add groups.

So, the first night you can add the Lights, Darks, Flats & Flat Darks into the Main Group window. Then put in the Lights, Flats & Dark Flats from the second night into Group 1.....etc and stack them all together.

If you use the same exposure settings & sensor temp for both nights then you only need to one set of Darks, likewise, if you left the kit setup and didn't move the camera or focus then you may get away with only using the one set of Flats & Dark Flats as well.