Referenced 3DM not staying as sub layer

When using the “Insert” command to import a 3DM using the settings “Link” and “Reference”, the greyed out “> (layer name)” that results cannot be a sublayer. You can move it to become a sub layer as you work, but opening the file the next day will move it back to the top layer level at the bottom of your layer tree. I suppose there is no fix to this as of yet, is there?

The whole functionality of having referenced 3DMs is great though. But why do they have to be blocks?

If the file is to be used as reference but not modified, try using Worksession to attach the file.