Refi on blanket loan question

[Daniel B.]

We have two properties worth approx $220,000 and $125,000. We (my wife and I) have a blanket loan that is now $169,000. This loan is amortized over 20 yrs but had a balloon after 5 yrs (4 1/2 remaining). We are looking into refinancing the larger property and can do 70% LTV at 30 yr 4.125% with no points and minimal closing costs if we open accounts at the bank offering the loan...

The question we have is regarding the remaining $15,000+ balance. We may pay it off at closing but were wondering when a blanket loan is normally refinanced, will they recalculate the payment on the remaining balance, therefore lowering it, or is it like when you pay extra principal towards a loan, the monthly payment stays the same?

If the appraisal comes in lower than expected it could wipe out a chunk of reserves and future down payments if we have to bring extra cash at closing. The bank we want to do the refi with will not count the rental income on these properties because we have not had it for 2 years, if we keep the $1130 payment and add a second mortgage payment it will stretch our debt to income ratios.

The larger property rents for $1725 total (2-unit) and the other property rents for $1150.

I am on this site a couple times a day reading & learning and greatly appreciate all the help & advice.
THANK YOU!
Daniel