In QGIS how can I have more then one coverage layer in Atlas? As is shown in the image below I have multiple city blocks (in a layer), that contain multiple land lots (in a different layer). I wish to generate various maps (like the one in the second image, highlighting a different land lot each time) where Atlas could go first through all the land lots polygons inside a city block, then again in all land lots inside another city block, and etc.
You can create the combination of the two geometries and use this as coverage layer for your Atlas. There are at least three possibilities to add the features of the two layers. The first (and preferable) one will not create new data and any change in one of the two initial layers is automatically reflected - that comes as close as possible as using two layers as coverage for the atlas:
Use this virtual layer as coverage layer and you're done.
Options 2 and 3 are good to create actual layers in case using the virtual layer should be unstable. However, changes in the initial geometries are not refelcted and new data is generated.
Use Merge vector layers tool.
collect_geometries( aggregate('plot', 'collect', $geometry), aggregate( 'building', 'collect', $geometry) )