Is it against any laws for a former Landlord to contact the present Landlord?

As Landlords of an eviction we need our former tenants new address to file a wage execution. Although it was a non-payment of rent eviction we never got a dime from them and they owe us 4 full months rent plus damages and stolen items. Our tenants didn't entitle us to a forwarding address. Through our City Hall we found the owner of the rental property. So, I guess he's the new landlord. It's been so difficult and we are out a lot of money. Any ideas? Is it ok to make an address inquiry to the present Landlord?