The commentary to 12 CFR 1026.35(b)(1) states that 35(b)(1) (the requirement to escrow for taxes and insurance) applies to principal dwellings. Therefore, IMO your additional properties wouldn’t require escrow only the principal dwelling.
As for the loan modification/change in terms if it is isn’t a refinance then there would no change in the escrow requirements from when the loan was established. If the old loan will be paid off and replaced by a new loan then the new escrow requirements would be applicable. Take a look at 12 CFR 1026.20 and its commentary to determine if you have a modification or refinance.