The house is a 4 Family. each Apts has 2b, 1b , Building is in C+ condition on a B- Neighboorhood, Each apt needs a completely new kitchen and bathroom, which will cost 10k to 15k for each apartment.

@Conner Johnson flooring, kitchen, bathroom work.

In some cases a tenant can even deduct the cost of repairs from rent, if the landlord doesn't perform after requesting repair on essential items require to make the property habitable. 

It needs some work and was wondering if I could essentially BRRRR it with them still living in it?

After a decent amount of strong-arming my sisters are making me essentially sell one of the houses to my sisters husband.

And checking to make sure that box of 12 filters you left for the tenant actually contains LESS than 12 filters as time rolls on.You don't need a plumber to check connections but it's a good idea to check for leaks under kitchen/bathroom cabinets. 

I would essentially rehab it for the owner and give them the money they are looking to get to selling.ARV: $375k - $145k (rehab costs) - $125k (cost to "buy" the house from seller) - $26k closing costs = $79k left over.Holding costs would be just utilities and taxes since there is currently no mortgage from the current seller and I am never officially buying it from them.

Try and have them bid " apples for apples".1- Windows   , Vinyl, Low E.2- Six panel doors and no jambs but new trim.3- two tone paint, these two colors.4- New bathroom vanity, toilet, and remove old tile with new tile. 12' X 24".Etc , etc.Brent is smart and great article, I am just adding my point of view from a seasoned  Re- hab contractor!               

I have gotten creative, but as long as it has working bathroom, kitchen, and furnace, I have secured the loan. 

Added a bedroom and bathroom, pushged the envelope on custom design.