Thoughts on Debt/Income ratio on a joint lease

[Michelle Chevalier]

I am going to start this question by saying that I am completely green to being a landlord and I am looking for my first tenant. I have two girls, unrelated, looking to rent my house. They would be on a joint lease together. Both meet the income requirement of 3x rent on their own and have excellent credit repayment histories. One of the two has minimal debt but the other has a mortgage on a rental property that her family manages. With this mortgage, her monthly debt payments are almost as much as her income (I'm honestly not sure how she was even approved for the loan). How do I navigate this? Do I ask for bank statements? Proof of rental income? Or do I not need to ask for anything else since the other tenant would qualify all on her own?