In the old days you could send a message to a person that you were not connected with and they would get the message in their email inbox.
That changed a few years ago as Facebook created an "Other" inbox with your message, for messages from folks that you had no connection with.
Sounded good initially but everyone (including me) hated it because no one checked their "Other" box and there were no notifications to alert you.
Fortunately Facebook has seen the error of their ways and are changing the process.
As this Article suggests, you will now get a Message Request in Messenger that you can choose to reply to or ignore.
Thus, possible cousins that want to connect with you or vice versa will now have something with an alert so you know that a message is there for you to look at.
This will help all of us once again to use Facebook to try and connect with our possible cousins.
Thanks Facebook - better late than never.