Let’s say you’ve got kids. They like using Facebook Messenger to keep in touch with other kids to talk about Minecraft or bubble gum or whatever kids talk about these days (What? I don’t know. I’m 28, so I’m basically a million years old in cool-stuff years.)

You’re happy to let them use Facebook Messenger in the evenings, but you don’t think they’re quite old enough for a phone of their own just yet. What to do?
Facebook has just simplified things a bit, adding support for multiple Messenger accounts on one device. 
Facebook released this update to android phones on 21-Feb -2016.With this feature you can add your other user account and both of them can use this messenger simultaneously.Today I am giving you tutorial on how to add multiple accounts on facebook messenger.
How To Add Multiple Accounts On Facebook Messenger
Step 1:Update your Facebook Messenger app and open up your app.
Step 2:Once your Messenger is opened up navigate Setting tab and you will see 5th option as ‘Accounts’, Tap on it .
Step 3:After your tap on ‘Accounts’ in setting tab on top right corner you will find ‘+ button’  tap on it , a pop dialog opens on Accounts to fill usename and password of other account.Fill in details and your logged in.

How To Add Multiple Accounts On Facebook Messenger