The feature was available on Android since February, and allows you to add multiple accounts to switch between. That’s great news for social media managers, small business owners, public personas, or family members who share a single device.
The update makes the entire Facebook app family (FB, Messenger, Instagram) all capable of switching between multiple accounts without constantly signing in and out.
You should see the option under Profile > Switch Account > then see the plus sign to add a new one. Happy messaging.