Guess your borrower's credit was so bad the couldn't open an account or owed some bank or really can't manage money.

First is keeping track of who invested what, who is owed what and when they are owed it.For that, unless you are talking about tens or hundreds of people, a simple Excel spreadsheet should be fine.

She owes $129K ARV is $161 (appraised).

Right now he owes about $90k on his property, and has $30k in personal loans from his sister.

I will be meeting with a potential seller and I want to be able to deduct from his asking price plus what he owes.  

Anthony Gayden  The fact someone can or cannot pay their mortgage from the rents depends on how much they put down on the property to begin with, and the balance owed on the loans.

It helps that I am a principal broker, only do commercial real estate investments, and I am an investor myself. preservation of capital and buying right is key to long term success.I think your agent sounds like they want to help but lack the experience to do so.A newbie investor and a newbie investor agent is trouble.

@ Chad LopesDo you think its better to use the cash flow for another investment rather than pay down principal?

Think of it like creating an entity that exists specifically to play the role of the character conducting business activity in your best interest, that will also play as the role of the filter for anything earned or owed.

I only include known numbers...in this case principal, interest rate and PMI as stated by Robert.