ReadyCloud sync

Does ReadyCloud for iOS and Android support sync but in both directions ? Or always from device to ReadyCloud?
Because right now for example if I make a full backup of my photos from my iPhone I will backup all pictures and for example some of them are made by mi kids which aren't sufficient to be left. But after making that backup when I erase that picture on phone will it be automatically removed from my backup or will it be left behind? 

If not it would be a great feature to add don't you think? Specially when there is option in the app to make backups on fly which isn't bit effective when someone does a poor picture with your phone (kids example) or even me and I decide to erase it but it will be already putted on my NAS and takes size.