Multicast a OSD image to all subnets simultaneously with only one MDR. Broadcast and multicast ports are enabled for all subnets

How can be forced a multicast software distribution task to select only one MDR for all the existing subnets in a corporate network. In my case the Broadcast ports and multicast ports are all open in all routers, and we look for sending an "all out" multicast distribution task to only one "global" MDR to serve and deliver to all subnets in a row. Is that feasible?

Corporate servers are limited to deliver a file to a maximum of 9 simultaneous connections, and this is a handicap for deploying thousand of OSD images simultaneously. Our proyect requires to deploy a single image to hundreds of subnets with only one MDR for them all.

Thanks!