In this scenario I personally as the PM would probably opt to not apply it towards the late fees since we didn't collect the rent, even if our PMA said we could, because I understand that sending an outstanding balance to collections has a low likelihood of success. 

It’s key to balance both when building your portfolio.Need help with financing?

And like you said if getting that balance down below a 25 year commitment is most important to you then by all means keep paying the extra $100.

Entities that are not "disregarded" need their own QBO to ensure their balance sheets remain 100% accurate.We do run into an issue every now and then with some transactions that don't allow us to designate the customer/property but we've found ways to get around this and still have the transaction reflect the appropriate customer/property.This allows us to pull all the financial reports our Clients and their tax pros need to see.I'm in no way saying our way is the end-all-be-all but it works for us and our Clients' tax filers/advisors.There's a FB group called, "Bookkeepers for Real Estate Investors".

Give them an out now and balance the cost of that against them leaving the place wrecked leaving the non-op vehicle.  

You're entering into a phase of the investment journey where you want to strike a balance between proper due diligence and avoiding last minute analysis paralysis.

Then find the perfect balance for your situation. 

This balances maintaining your current property and expanding your investment portfolio, although it involves higher mortgage payments.Given your goal to minimize your ex’s financial benefit, selling your current home and purchasing a new house hack might be the most straightforward and financially advantageous route.

Get a credit card (at 15 you can get one as an authorized user- Google it) and make certain you pay off the balance every month. 

Ensure major decisions are made jointly.This setup balances the partnership and fairly rewards both contributions.