@RadioActiveLamb - make life easy on yourself as this area of TT has always been a headache. Just enter all the mortgage interest related to the new home on one 1098. I wouldn't split it up the three 1098's as in this case you did not pay off the loan or refinance it. (had you done that, my answer would have been different).
List the 1098 for related to the home sold separately.
The IRS doesn't do matching on these forms, so it won't create any hiccups when you file.... and if you ever get audited, you have the supporting documentation showing that you just summed all 3 together.
I appreciate some may not see this as the 'kosher' answer, but it is the expedient one with no real risk.
