If anything I think North Wilmington should be the stop replaced by a new I93 station. North Wilmington is in a low density neighborhood, with no TOD and only 20 parking spots. Adding a garage to Wilmington train station, plus a new I93 train station could serve people from that neighborhood.
Plus North Wilmington gets its last train of the morning at 630 AM and doesn't get another one until 930. A 3 hour gap at the peak of rush hour. This is because the two rush hour trains just past 7 and at 8 am go onto the Lowell line.
https://www.google.com/maps/@42.5907999,-71.1638484,1613m/data=!3m1!1e3?hl=en
This is where the Haverhill line crosses I93. I'm not sure if there are any wetland restrictions there that would preclude the building of a new transit station (F-Line probally knows more). But that stop would be closer to North Wilmington than it would be to Ballardvale.
I'm not sure why you'd get rid of one of the Andover stations, they aren't close together and they do get healthy ridership. It's not like Winchester where stations are within easy walking distance.