Third.  10-20% under markert value rents. 

Has been rented now for six years.

or rent it out and downsize my life to save more.If I rent it out my property taxes will go up to 6% since it will turn into an investment property. 

I must do this to rent the unit.

Her family is telling me that landlords don’t have a lot of say in renting with not being able to evict during the cold months if the tenants have children.

Will get us a good bump in rents and added mini splits HVAC and removed the old in wall heaters that weren't very efficient. 

@JD Martin - FYI, she was an inherited tenant when i acquired the building and had always paid rent.

My suggestion was going to be to prorate the monthly rent for sake of starting the relationship on the right foot. 

But after that ... hell, move out and you've got a duplex in what otherwise would have been single-family zoning.As it used to be in Denver and Colorado Springs and most cities in the state, you could rent an ADU separately when you live there, but once you moved out, you legally could only rent the whole property to one party. 

I used their ultimate plan, which has rent and eviction protection.