How much value would a 2nd home with 1800sqf 4bd 2ba add to a property worth 175k?

[Jorge Morales]

I’m looking to purchase a property that has a home with 3bd 1 1/2 ba, and connected to it is a recently built 2nd home with 4bd 2 full bath and 2 half bath and is vinyl . The original home looks to be valued around  175k-195k and is all brick. Only thing is that they are connected in the basement and utilities are combined. I’m trying to get a rough estimate on how much it would be worth since i think there’s a good chance a might use a hard money lender if possible to purchase the property and keep it  as a long term rental.