You come up with an agreement to pay them back based on a predetermined plan - most of the time based on the interest rate and term (or length) of the loan.  

I may give them options, but they are my predetermined options for color or materials.

Hi Kenneth,Yes, but when renting--make "Business Decisions' about who will rent unit #2.What I mean is don't just accept someone because she is a "Hot Cha Cha" (you know what I mean).Keep your "Business Life" separate from your personal life--because it will most likely cause you business troubles if you don't.Pick you renters according to a predetermined plan (look in this forum for ways others do this) and vet them properly--they are going to have pay the mortgage with you.Also in a duplex the two sides must get along.If you sleep all day and apt #2 practices the tuba all day...Ouch.Just my 2 cents.

don’t you set a pre-determined rate in the lease option?

Also, thinking through this "lens" of a life estate, is there an alternate route that has the same outcome of me getting first right to purchase at a predetermined amount?

Additionally, you can safely be compensated a 3% acquisition fee, ongoing management fees in the 1-2% range, normal property management fees if you do this in house, and “performance” fees after your investors receive their investment back plus a pre determined return.  

✨Exit StrategiesThe exit strategy—or the sponsor’s predetermined strategy for selling the multifamily property at the conclusion of the syndication—is another important component of the investment documentation.

If the architect was a part of the construction phase and being there on site to do periodic site visits, that correspond with certain predetermined phases, the odds that this would have been caught at a stage where it could've been fixed go up dramatically.  

For refinancing, aren't you taking on a loan with a predetermined time and interest rate?  

Lowest priceRecommended- is based on number of types of units available, Move in versus reservation %, views.Distance- measured from a predetermined Post Office Station location.