From my notes (not like to re-invent the wheel)
The DR and BDR form a full adjacency with each other. Every other node forms a full adjacency with the DR and the BDR. DROTHERs only go to the 2WAY state with each other.
If an LSA is ORIGINATED on the DR (because the change happened on that router, or on something connected behind that router in a different subnet), the DR sends the update to 224.0.0.5 directly. All other devices respond with an acknowledgment, the DROTHERs do this on 224.0.0.6, the BDR on 224.0.0.5.
If an LSA is originated on the BDR, the BDR sends the update to 224.0.0.5 directly. All other devices respond with an acknowledgment, the DROTHERs do this on 224.0.0.6, the DR on 224.0.0.5.
If an LSA is originated on a DROTHER, the DROTHER sends the update to 224.0.0.6, and the DR sends it to all other routers, including the BDR, on 224.0.0.5. The BDR sends an ack, acknowledging the DR's rebroadcast on 224.0.0.5, the other DROTHERS send an ack, acknowledging the DR's rebroadcast on 224.0.0.6.