One way to do that is to support group video chats, which Facebook Messenger now offers. While one-on-one video calling has been a feature supported by Messenger for some time, the addition for groups to video chat will likely be a welcome addition for heavy Messenger users.
The group chat also supports up to 50 people with text and audio, but as mentioned above, only six people can video chat at the same time.
You need the newest version of Facebook Messenger for group video chat to work. It’s rolling out now for Android, the web, and iOS users.