Map layers to stay attached to the iModel when an iTwin is referenced in MSTN/Open Roads Designer

Currently, when an iTwin is referenced in ORD/mstn, any Map layers attached to the iTwin are not persistent. If they could be viewed in the design app, it would be very helpful to many DOTs who want to see more than just SHP file data from their GIS. I know that at minimum this could be helpful to Iowa DOT, DelDOT, PennDot and MissDOT.