Having the original date of the mortgage origination is correct. You did not get a new mortgage, you are only paying a different company.
The terms of your mortgage stayed the same as when you originally borrowed the money.
Since you said that the box 2 is blank on the new mortgage company 1098, you may need to enter the outstanding mortgage balance shown on the previous mortgage company 1098 to proceed.
[edited 4/6/19 | 8:52 am PST]
