Why do Overviews convert to primary in Derived Mosaic Datasets?

[WillMcInnes]

Software: ArcGIS Pro 3.1.3
Drone orthomosaics stored in Source and Derived Mosaic Datasets(MDs).
Overviews are created on Source MDs as suggested in documentation.

When adding a Source Mosaic Dataset to a Derived MD (e.g., combining multiple projections or pixel types into a single dataset), the overviews from the source get converted from "Overview" to "Primary" category.
This is expected behavior per this documentation , but why? I would like to be able to only show footprints for Primary Rasters and not overviews, but have to do a bit of a workaround to get it working.

What are the implications of changing the category back to "Overview"? Is there some reason why Overviews become "Primary" when added as a Table / Raster Catalog?

Any help or insights appreciated!

[YuriPotawsky]

Hey @WillMcInnes.  My assumption here is that when source Mosaic Datasets are added to the Derived Mosaic Dataset they are added as individual table records. Therefore the cell size ranges are recalculated and I confirmed this behavior.  As you pointed out it is expected behavior but you could change the ov_ files back to overviews and then use the "Calculate Cell Size Ranges" GP tool to redefine the min, max, low and high PS values at the footprint attribute table level. 

Another option would be to create source mosaic datasets without overviews and then define and build them once added to the derived. You could define a query and/or aoi's based on a variety of factors. You can also deselect the "Update Cell Size Ranges" parameter in the Mosaic Post-processing section which will enforce the cell size ranges from the source mosaic datasets.

Yuri

[WillMcInnes]

Thanks for the reply @YuriPotawsky ! Yes we are adding records to the Derived MD as Table Type.
 I will try to convert the ov_ files back to overviews. I couldn't get a straight answer from support about whether that would cause any issues, but I will try it. I will just have to be careful with synchronize when we add new rasters to source that it doesn't blow away the overviews on the derived MD. Calculating overviews on the derived MD is a good idea to try also.
What is the significance of the Raster Type ID Field? I can't find any documentation about it.