I feel there is a fine line and also see a lot of houses sit on the mkt for 2-3 months since they started too high and missed on a lot of rent so there is a balance both ways.  

Default owed, condition of property, loan balance etc and after repair value, then based on where you offer is, the offer that is accepted, its about what makes sense to make your money.

The buyer typically makes a down payment and then makes monthly payments until the purchase price is paid in full.Wraparound mortgage: A wraparound mortgage is a type of financing in which the seller provides a mortgage to the buyer for the balance of the purchase price, in addition to any existing mortgages on the property.

Or at least counter balance info with like a Mike D Arrigo interview perhaps.

This is a perfect balance between giving the tenant what they want and also protecting the condition of your rental property. 

And what should I do if I get less than the balance again?

This is a fine balance and if set to low you might start getting complaints.  

It all has to be carefully balanced and not to get greedy, fairness is first. 

My furthermore questions are: Looking for a technique to avoid disrupting my current mortgage if title/deed name change is required to engage lender and that lender calls to accelrate mortgage, and i need to pay-off remaining balance in 1-month.?   

One of the factors would be your mortgage balance and rate.