The more the merrier
Definition 1 of 1
Pro Tip 1/3Group Inclusivity
Implies everyone is welcome, emphasizing inclusiveness in group situations. 
Don't hesitate to bring friends to our game night, the more the merrier!
Pro Tip 2/3Casual Tone
Used in informal settings, like casual get-togethers or personal invitations. 
We're having a barbecue this weekend, the more the merrier!
Pro Tip 3/3Positive Vibe
Conveys optimism and is often used to encourage a cheerful, upbeat atmosphere. 
I heard more people joined our book club, fantastic – the more the merrier!