Posted in the wrong forum - moved to the RS forum.
First, you live is a RS apartment, not a RS building. There are no RS buildings.
Sandy was five years ago. What have the tenants and LL been doing about this for five years? Why is it an immediate need now?
It sounds to me what they are doing is not legal. I would first speak to a tenant attorney who has experience in this sort of thing. I'm not familiar with Sandy-related displacement issues, it seems to me to be analogous to tenants who are displaced due to a fire.
So see viewtopic.php?f=15&t=5973 in the forum's Reference section.
If other tenants are also being displaced, then you can speak to an attorney as a group ... you should form a tenant's association if you don't already have one. You have more rights as a group. If one or more tenants are low-income, the group might qualify for Legal Aid, Legal Services or MFY.
But in no uncertain terms should any tenant agree to a relocation without an iron-clad agreement (negotiated by tenant lawyers with the LL regarding their return. The landscape of NYC is littered with stories of tenants who were told they could return and found out later that the LL has rented out their former apartments to new tenants at higher rents.