You will need to allocate the expenses between the personal and rental portions of the house.

This division is standard unless Cousin A and Cousin B agree to a different allocation of income and expenses in a written agreement.

Is there a way where there is flexibility to the % allocation of income/expense? 

I But because the lender can allocate those riskier loan into bunch of other mortgage loan that's more "safer", the lender can somehow reduce their risk, also by requiring the borrower to purchase interest rate caps as hedges and so on.

For example, a 10% return (or reward) can be worth the risk if you are investing in a Class A single-family rental in a great market with an A+ tenant, but not worth the risk at all if betting on a 16-seed to make it to the Final Four in March Madness.Investors in mortgage bonds utilize the risk-and-reward framework when allocating how to invest capital.

And this means the deed must be allocated appropriately between the tic owners.If you're buying the property under your name and are trying to get primary residence financing that is where you may have trouble with the lender. 

The rates more than double resulting in near doubling of P&i, the cash flow (after allocating for all expenses including P&I) falls to poor or negative with no value add to save them.

Of that 50M, 25M was allocated for the construction of a new recreational faculty that has since been completed.

Instead, they miss the cloth or aluminum wiring and poor circuit allocation and instead show you with their fancy plug that "polarity is reversed"; or the always arbitrary "the roof likely only has 5 more years left max" because they see a 3-tab shingle from the ground and completely miss hail/wind damage on a newer architectural shingle citing its "lifetime warranty".

At high LTV, you need a ~1% ratio in my market with the current rates to be cash neutral if properly allocating for expenses.