I have a polygon layer containing polygons vectorized from a raster image. After changing one polygon several smaller polygons are now contained within the first. I could now add a ring for every small polygon by hand using the snapping and tracing but this is very time consuming.
Is there a way to add all this rings automatically?
I use QGIS 2.14.3 with GRASS tools enables.
Edit: I added two examples of what I have now and what I want to get.