If you're looking at hard money, it's brutal and will likely eat up a fair amount (or ALL) of your profits.

Okay, G buys a dumper for 12k, puts lipstick on and makes repairs, 5K, puts Sandy the scammer in, pays 500 in rents (but he gets most or all back) sells for 35K that works out to good ROI, fakes docs.

If you don't have all the money or all the stars have to line up to be able to purchase be ready to drop tens of thousands or more in non-refundable earnest money of your own.

If a life changes occurs one of the siblings will want to sell or it might be 2 or all 3.

In many structures, the investor benefits from depreciation that offsets some or all of the income (which creates a temporary tax shelter). 

These may include cracks or settlement in the foundation, water seepage, active roof leaks, curled or cupped roof shingles, inadequate electrical service or plumbing fixtures, etc.

But other than that, they are only somewhat inadequate at what they do.

I'm still a bit confused on your HELOC scenario, are you basically saying that if he ties up most or all of his $180k cash buying and/or rehabbing the first home, you'd want to get a line of credit based on the value of that first home purchased for cash, thus to use the HELOC funds to buy and/or rehab more houses?

Most buyers want you to pay some or all of their closing costs, another 3%.

Depending on your financial support system you may be able to close on deals in one or all of the above mentioned.