Confirm with your lender and agent, though. 

Obligo confirms their accounts and approves them, then charges then $15 a month while promising to cover up to $1,600 for any claims I file.Rhino is another option, more like an insurance policy.

I would check with your financial institutions to confirm their seasoning requirements.

You're correct, in addition to higher rates and fees when obtaining a HELOC for an investment property, there are also stricter approval requirements (high credit score, LTV ratio, gross rental income, cash reserves, etc).

How do I confirm that the animals are in fact service animals? 

If you are dead set on a HELOC you will likely need the following for an investment property: An excellent credit score (720 or higher), A maximum 80% loan-to-value ratio, Healthy cash reserves on hand, Sufficient income from tenants, Additional features that make the property attractive, like whether it has long-term tenants (Source https://www.rocketmortgage.com...)

However my real concern is you mentioned that your bills depend on their ability to pay as well which implies that you don't have sufficient cash reserves to handle financial hiccups without putting yourself and your family in a financial tight spot. 

But keep in mind, the best influencers are the ones that are able to influence others without others even realizing it.Here’s a list of all the people that I influence when it comes to real estate investing:my bankers through keeping enough in reserves and having enough cash flow to lead them to want to give me loans on my properties.The people who work for me by being nice to them, encouraging them, providing a good work environment, paying them, and helping them get their own real estate properties.My business partners by trying to be fair, making sure that they benefit from the partnership, and by helping them reach their goals all while helping me reach mine.My tenants I incentivizing them to take care of all the smaller issues that come up in the home by discounting the rent.Sellers by finding out how much they need to get out of the sale of their home in order to help them solve the problem that they’re in, then we work together to make it a win-win situation.Title companies by sending them previously closed settlement statements explaining how to put the rehab credit on to the settlement statement.Wholesalers and realtors by telling them that I own 200 properties and I am a serious buyer and  that I will buy the property if I am able to buy a property A certain way or at a certain price, and that I will close on the deal as long as it is according to how they presented it. 

That said, I'd make sure you have your financials ready in advance - already have your lending ready to go and/or have your cash reserves ready to go. 

It's also more difficult to evict them.Here's some other helpful previous posts info:Please review the list of items below regarding each unit and confirm what is available and if it can bedelivered by mail, scan & email, fax or pickup: For each occupied unit: current lease, move-in checklist, etc.