How to run many rman backups from OEM 11g using a single rman backup job?

I have about 25 databases. I do a Level 0 backup on Sunday and a Level 1 back on the other 6 days of the week.

I would like to create a single OEM backup job that runs (rman script) on all of my database targets for the level 0 backup and a second job (rman script) for the level 1 backups.  This way I only have to schedule the entire job to start at one time and all databases are backed up one after the other until they are all done.  However, when these run all 25 backups are started at the same time and run in parallel which kills the server. I want them to run serially, one after another.