I recommend you take a look at the Pair States section in the SRDF CLI product guide: This will help you understand the R1, link and R2 states with the various SRDF operations.
A RESTORE operation makes the data on the R2 device the master and it will overwrite the R1 data. An ESTABLISH is the opposite, R1 is master.
Perhaps you can familiarise yourself with all of the available SRDF operations as it sounds like an SRDF SWAP may be useful to you if you want to write at each site from time-to-time. SWAP will make the DR site the R1 so you will not loose DR protection.