Factoring in rental property owned <2 years in DTI calculation

[Catherine Y.]

In the early spring of last year (2019), my brother, mother and I bought an rental property that none of us live in. It has two units, and both are currently rented out. I claimed the property on my tax returns (Schedule E) because I am the person that primarily deals with the tenants. 

I was planning to purchase my first home (primary residence) this fall but am now slightly concerned about how the rental affects the DTI calculation.

From reading other posts, I saw that generally if the net income is positive then it gets added to the income portion of the DTI, if negative, then added to the debt portion.

Does that still hold for rental properties that are less than 2 years? If so, how is the net income usually calculated? I’ve seen variations from different posts and was wondering which method is used most often (0.75 * rental income - PITIA, rental income - mortgage, calculations based on schedule E - PITIA). One unit has a tenant with a one year lease on it, the other unit’s tenant’s lease expired earlier this year but has been continuing to live there on a month to month lease until the end of this year. Do I need to consider that arrangement in the calculation?

Or would the full PITIA be added to the debt portion in the DTI calculation since I've had the property for less than 2 years? I've read in other posts that the income must be seasoned in order to use it, and 2 years is usually the time period.

Is there any consideration for the fact that the property is jointly owned? Ie, does that net income / full PITIA debt (depending on the answer above) get split three ways before added to the DTI calculation in my scenario? 

If the full PITIA is added onto the debt portion in the DTI, would a more flexible lender be able to work with that, or would I need to just wait until next year before purchasing a home?