I have made a few projects in the old version of BLYNK. In some of these I have used the Bridge to communicate between the devices. For instance in my NFC lock project I have a card scanner on the desk that gets used to provision new cards. It sends the data to the locks and the locks also send data back to the scanner when doors are opened or cards are scanned at the door.
I am not sure how to replace this in the new BLYNK.