In the ArcGIS Pro GUI and with ArcPy, I can add a Mosaic Layer (a Mosaic Dataset dragged to the contents area) to another Mosaic Dataset with Add Rasters and Raster Type Table.
arcpy.management.AddRastersToMosaicDataset("input_mosaicDS", "Table", "Mosaic_layer")
Is there a way to do this with the config file of an MDCS. When I put
<AddRaster>
<dataset_id>DTK_$land$_$datum$</dataset_id>
<raster_type>Table</raster_type>
<Sources>
<data_path>mosaic_layer</data_path>
</Sources>
</AddRaster>```
the Mosaic dataset is emtpy. I can create a MD in arcpy and then import it into antoher with MDCS, but of course it would be more elegant importing the layer directly.