@Red1 

It wouldn't.

If that was the case then the iPad and iPhone would connect to every wireless network it came across that was password protected.

A device will be able to connect to the wireless network if the name and password were the same as the old network or if there was no password configured for the wireless network.

I set up the new network. The SSID and the password were never used before. I received notification on the deco app that the iPad had joined the network but did not receive a request to share the password via my iPhone as normally happens between iPhones.

@Red1 

If the capability is there for password to be shared then that may be going on another way.

With the Deco unit is password protected, it will not allow any device to bypass the password and connect to the network.

@Tony 

Before the network is shared, I have to agree by clicking on my iPhone in response to a notification that pops up. I don’t know why/how the iPad and iPhone were able to connect without my accepting their requests. Everything has been behaving as expected since, with new devices requiring the password. I just figured TP-Link might want to know it happened. 

Thanks for the replies.