May I ask why you prefer the Terrain? Having a second child comes with having a lot of “stuff”. Not only is the Acadia (or Traverse) a better lease value, but it would provide you and your family more space.
See this thread regarding the Traverse:
Have you sat in both vehicles with a forward facing/rear facing car seat behind you? Are you familiar with seat back failures and the effects on children sitting too closely to front seats?
I refuse to cramp my kids behind a front seat. I am
6’8” which requires my family to have two large vehicles.