Basically I hope to build investment property portfolio over the years hence I am looking for a good agent with whom I can build a relation.

The units are basically turn key would paint the inside and fix a couple minor things maybe 500 bucks.

Basically, anything other then 25% down and bank financing could qualify.Using a HELOC for a down payment is a pretty common strategy.You need to look at what the extra costs of the HELOC will be and figure that into your calculations, probably off-line in a spread sheet.

Hi John, Nothing about this would be easy but I would apply basic wholesaling steps. 

Which basically means that if the property changes owners, they could call the loan due.

Basically, they'd want you to have 20% of the $3MM to qualify for the LOC. 

I know that the unit was bought in 1999 for basically nothing, and now it worth around $300 K.

Identifying lenders is basically a waste of time until you have a property under contract, ditto for interviewing attorneys, accountants, etc.

We had a super detailed letter from the dad-in-law on how the husband made a massive game changing contribution to the business, whole 9 yards, didn't cut it.We don't have all the details of your scenario, but when you mention dad as both employer AND cosigner, it starts to share elements -- "the dad obviously really wants you to get the loan or he wouldn't be co-signing, can we really trust those paystubs from said dad?" 

Some other basic steps are pay of high interest rate credit cards, student loans, and any other debt, set up an emergency fund, and buy some life insurance.