The software on the devices has to be complicit. The cloud has little to do with Device A’s explicitly turned off connection capability being able to be turned on and left on by (previously linked) Device B’s request for connection.
All they really had to do was connect to her email account and retrieve all the mail. You can have as many clients as you want.
See #153. I’m an Apple newbee having just obtained my own hand-me-down Apple device to explore and play with within the last month. Linux, ‘Doz, embedded assy, and Android toys before this recent trip into the alternative universe.