Can air bnb income be used to help qualify for a loan

[Jacob D Adamczak]

I am under contract to purchase a house with a ~600sf guest house in the back yard of the property that has been used the past 3+ years for Airbnb. It is my intention to continue to use it for STR and it should pay for the entire mortgage. I was planning on using the income from the property to help me qualify for a loan at a higher amount than my W2 job could qualify me for without this income. My question is this, I have one lender who thinks it is no problem to be able to use this boarder income to help qualify, one that says air bnb income cannot be used to help qualify and I would need a signed lease to use rental income, and a 3rd that says the only way that I can use the income is if it is zoned as a multifamily property and I get a loan as an investor which means higher property taxes and rates. Hearing 3 very different things, I am pretty confused as to who is right, any help is appreciated!