DR Testing and Source site data lost io Celerra Revers replication

If some one Failover Source site  to Destination site, and the Destination Site was not upto date, Then how can Rollback or Reverse and any thing else to avoid Data Loss on the Srouce updated site?.

If some one Switchover and reverse back from Non-updated Destination Site to an Updated Source Site. If the data on Source site will be lost?

If some one started Revrse replication from Source Site to Non-updated Destination Site with checked on Descard changes on destination since last copy, then Data can be lost at which site?

If Data lost due to Reverse Replication from  a Non-updated Destination Site to Updated Source Site, and Data lost occured at Updated Source Site,  then how the Lost Data be recovered?  Please response with any correct suggession...