The best way is to form a relationship with them, which is one of the ways that sponsors demonstrate that investors weren't introduced through a general solicitation.Aside from investing in syndications, if your goal is to own real estate directly, and you want to move up to larger properties, there is no "rule" to prevent you from doing so. 

Most major cities have strict zoning laws to prevent this from happening. 

Additionally, it would tie up my investment capital for 10-12 years as I pay down the HELOC and prevent me from further investment.

As I mentioned before, the bank has redundant language in their boiler plate that prevent buyers from doing this.   

For beginning investors looking into asset protection I often break it down into the 5 pillars of asset protection (but there are many more.)1st pillar is avoiding unnecessary and risky activities (don't drink and drive, insurance generally won’t cover your poor decisions) and take good care of your investments - these simple steps will help you prevent lawsuits before they even occur.2nd pillar is a good insurance policy as that cover the majority of your exposure.

I have to go there and stay up all night like a security guard to prevent these scary gathering and it's taking toll.

What is preventing the "partner" from just reaching out the the seller themselves and taking the deal alone if they are experienced.

Is there any laws preventing targeting foreclosures in DC like there is for Maryland ?

Nice.Any good short sale listing agent has a ton of contingencies to prevent exactly this from happening and you are not likely to have success unless you find an incompetent listing agent...Even then you will still need to prove your ability to purchase upfront, and you will lose your deposit funds by breaching contract. 

I often break it down into the "five pillars" of protecting your assets.1st pillar is avoiding unnecessary and risky activities (don't drink and drive, insurance generally won’t cover your poor decisions) and take good care of your investments - these simple steps will help you prevent lawsuits before they even occur.2nd pillar is a good insurance policy as that cover the majority of your exposure.