If you are directly negotiating it please insist on it being nonrefundable,  and for it to be a significant sum proportional to the length of the contract.   

...What is your average resident length of stay?

a pro tip that i've gathered is to look into term life insurance policies for each partner. here's why:partner #1 gets a term life policy with partner #2 listed as sole beneficiary, vice versa. they determine term length & value based on about how long they plan to hold the property, and about how much equity each of them will have in the deal at that time. partner #1 passes unexpectedly. rather than partner #2 having to default to going into business with #1s family, it's written into their partnership agreement / trust docs that in this situation, #2 has the option to buy out #1s interest in the deal. #2 uses the proceeds from #1s life insurance policy, to buy out their half, and #2 is now sole owner of the property.these are the things that no one wants to talk about, but discussing all possible 'worst case scenarios' up front with a potential partner can help you avoid some sticky situations. it also provides all parties with peace of mind, which allows for way better business decisions to be made.this is not legal or financial advice; this is a suggestion to talk with your insurance broker and see if this would suit your partnership's needs. and remember: partnerships can take any form!

You need to be sure you can handle this cash bleed not only for as long as you think it could take to be cash neutral but you need to use some worse case numbers (maybe double the length of time you expect). 

I could talk about the Columbus market At length!

Due to this, your mortgage length (TIME) will be reduced. 

This is NOT based on the lease, but actually based on the length of time they have resided in the property, per the Housing Stability & Tenant Protection Act of 2019.You are in over your head and have already made some mistakes. 

However, we have to give 30-90 days notice depending on the length of time they've been at that residence.  

All are fact-specific.Factors to consider:Type of collateral (residential/commercial, secured/unsecured, asset class)Location of collateral (which state)Length of termType of borrower (consumer/commercial, human or entity)Type of lender (per SEC definitions)Structure of the debt You see, some debt can also be a security under SEC regulations. 

Leases need to be 30+ days in length so a month to month tenancy works well.