Check out iGlobal and the Independent Sponsor Forum of the Small Business Investor Alliance. Both host events in various cities throughout the year. Their events are a mix of networking and content. They are well attended by independent sponsors, capital providers and service providers. Opus Connect also hosts a few events. I'm quite involved in the independent sponsor space, so feel free to DM me or email me at redacted if you have any questions.

Hey Avinash, I'm not aware of any formal groups, outside of the conferences mentioned in the comments. That being said, when you go to these conferences, you'll meet many other independent sponsors who are pretty helpful and willing to provide their perspectives, intros, etc.