What kind of properties? Business property? Residential Rental property? Raw land? A mix of property types? Something else?
Assuming 4 different rental properties, how were you reporting them on your tax return for the rental income/expenses? As four separate rental units maybe? Is this a multiplex setup with all units in one physical building? We need details. Otherwise, you'll end up with an encyclopedia of which 99% will not apply to your specific situation.