Re rent roll, obtain copies of the executed leases and validate collection via bank statements and tax returns. 

The total of all depreciation taken is taxed.

@Dennis Hill if the house meets standards of that size family, enough beds baths and room size for children, then follow your standard rules, like I make anyone 18+ years of age qualify on their own unless they are a dependent of main tenant (prove with current tax return).

Now you have a brand new property that has no mortgage, rents for $2,000 a month with $300 a month in taxes, insurance ect…profit $1,700 a month.

We are not married, but I charge her 'rent' which is a little less than 1/2 the mortgage.Are there any tax benefits to saying she's a renter and I'm the landlord?

There are several reasons for that including but not limited to, landlord friendliness, lower prices, population growth projection, positive job growth rates, lower crime rates, 1% rule, to name a few.

But there are implications to that strategy so be sure to discuss your specific situation with qualified tax expert as this is not a tax advice and I’m not a tax expert. 

I highly recommend it.If you have any other questions or need any bookkeeping or tax help, please feel free to reach out.

In this scenario, are both mortgages considered senior liens, or is the one recorded earlier in the book, indicated by the lower page number, deemed the senior lien?

BUT when you're doing an arbitrage you're just getting cash flow and you're missing out on the equity and tax benefits