But yes, a HELOC could certainly be used for purchasing investment properties, just ensure you have the cash flow to cover the loans. 

The rent on the property is currently covering the PITI.

If I want to cover all of my basis and I want to do more free marketing I would do the following for some low income rental properties:Facebook Market Place - back in 2019 to 2021 FB market place was amazing.

I do have sufficient cash of our own in our bank accounts to show we could cover the mortgage for ~6 months if it was unrented.  

Sure, I'll cover your first month's rent after they have moved out of your place, you have changed the locks, and they have provided you proof or a receipt of the first month's rent they paid to their new Landlord.

The clause will likely cover even things you state about them that are true.

Leverage Lines of Credit: Some people tap into personal or business lines of credit to cover the EMD.

So they now own a house that is rented and the rent covers the mortgage payment by a ration of 1.25:1 or so and they have 5k extra in their pockets and their Heloc money, which they only needed 75k - 80k of - so 100k HELOC should be plenty - was enough. to get through the lifecycle.Do not let them drain their equity from primary and just sink it into a project. 

We just need help getting in, the payments are covered!

Even if you have enough for a down payment and closing costs, there is always a chance the furnace or AC goes out the first time you try to turn it on (typically this would be caught by an inspector), or some major damage happens that insurance doesn't cover.