How co-borrowing impacts future debt to income ratios

[Albert Young]

I recently purchased a triplex with my in laws. It is a shore property that we plan on renting two of the units seasonally and keeping one unit jointly for our own use over the summer. Both my wife and I as well as both my in-laws are on the loan and title. My question is around how my debt to income ratios will be calculated when i go to buy my next property soon. Since I am legally responsible for the full loan even if no one else pays, I assume under-writers add the full monthly mortgage payment to be debt. But they will use my tax returns to determine income (of which I'll only claim 50% since my wife and I file jointly and own 50% of the property).

So for example, lets say the annual debt payments equal 2500 monthly. Lets says the rental income is 3,000 monthly. So my debt side of debt-to-income will increase 2500 but my income will only go up 1500?

This seems unfair.