Widespread overcharges in my building; "willful"?

[ChairmanNow]

My building is rent stabilized due to a J-51 abatement.

A DHCR rent history shows overcharges for the last four years in my case.

A helpful individual at DHCR also found a previous case for me, which indicated that the LL was made aware of such overcharging (as the case was decided favorably for the tenant).

Discussions with several neighbors indicates that they are likely in the same boat. They're all headed to DHCR to get their documentation to confirm, of course.

My question: if evidence is found, as I suspect, that this is systematic, what exactly is the hurdle to show that the overcharges were willful? What would a good course of action in terms of addressing the overcharges for multiple tenants? Is there a way to include former tenants? Is there any benefit (outside of cost sharing) for multiple tenants to band together in an action like this? I'd assume that the downside is that the LL has more to lose, and will fight a lot harder.

Interestingly, research has turned up, accidentally, that another building owned by the same LL may have gotten an abatement that it wasn't supposed to have. Not sure what, if anything, to do with that info should the hypothesis be confirmed.

Any advice, or PM's with attorney recommendations would be very helpful. This is for Kings county.

FYI, I'm a long-term poster and lurker, but I felt it circumspect to register a less identifiable name given the circumstances - hence no posting history.

Thanks!