There is no duct work and no lines for boilers.

Since it sounds like you already have duct work in place for both apartments, you can likely just have the existing system support the larger of the two apartments  and purchase another HVAC unit for the other apartment.  

I called in a Hvac contractor to get his opinion and he insisted that the duct work was built to heat a one family home and apparently putting another unit in (i had a gas line installed to the home 2019) would be very difficult to do assuming the lay out of current duct work so having it re routed would be difficult.

Also, have them put stoppers in sink drains, just to be safe.There's a chance they could be entering VIA the duct work/air returns as well. 

Could be in the furnace filter or the duct work.

When I toured the property it looked like the owners before had duct work ran supplying A/C to the garage, and it's all sheet rocked which tells me they may have intended on converting it and just didn't follow through.I'm really hoping despite the area though I could get a tenant or two for room rentals.                                                               

@Russ Wahl, markets will clearly vary, but here is a quick break down on my costs:Roof - 6,000 - 8,000Windows - $250-300/window installed for cheap optionDoors - $150 for cheap interior prehung slabs installed, and $500-1000 installed for exteriorHVAC - replace furnace and AC, but no duct work or electrical $6,000I would image you are at $20,000 right there, and these are not even the most expensive things. 

Plumbing - Must be functional with no damage or leaks.Hot water - Must be functional.Electrical - All receptacles must function normally, GFCI receptacles required in kitchen and baths, no exposed wiring.HVAC - AC is not required, but if ductwork is present, then AC must be functional.

Or brand new furnace ductwork with very clear finger prints they wouldn’t investigate.

So for the rehab, the plan is to replace all of the major components of the home: New HVAC unit (with additional duct work), new roof, new pool equipment, and an expansion of the driveway.Smaller items will be to redo all of the bathrooms, frame up walls to split the home in 2, and a new kitchen in the studio.Final Thoughts:    I hope everyone enjoyed this original post.