Local channel insertion is not required for DRM, as every DRM transmission is maintained by a single broadcaster. For DAB+ and DVB-T(2) services on the other hand, this could be a nice feature, as those are multiplex approaches where a single broadcaster is NOT in charge of their own signal component.
If you need to transmit a different composition of DRM services in different areas, you simply send a separately created MDI signal from the studio to that other region. However, with multiple broadcasters sharing the transmitter infrastructure in band II or III resulting in multiple DRM signals being broadcast in the spectrum side-by-side, every individual DRM signal can either be transmitted from only some transmitters in the SFN area, or from multiple or all transmitters.
This allows for a form of “local channel insertion” solution for shared transmitter setups within SFN areas.