Removing original foundation wall
I'm new here and never dealt with anything like this in my past homes, hoping to get some advice.
We bought a fixer-upper home on a lake and aside from some interesting ways previous owners added onto the place, they left many things in place. They added another 1/3 onto the house (on the west side) with a basement and never took the old west foundation wall out between them. There is also an original fireplace and chimney on that side that runs from the bottom of the foundation up to the roof. Again, they kept all this in place when they added onto the home and just sheetrocked around it all.
We are planning to remove the chimney, fireplace and 13' of the west foundation wall to adjoin the old basement and newer added on basement.
The roof gables "/\" on the west side of the house. The floor joists above are parallel with the west foundation wall as well.
My question is when we remove this old foundation wall, should we put up a couple verticle posts to hold the weight on that side? There is still the back (south) half of the west foundation wall that will remain in place. We bought 4 engineered beams 14' long for support. There is no longer going to be a wall upstairs from it, that was the fireplace/chimney so the only weight on the old foundation location would be from the roof.
Any help would be greatly appreciated, you all sound like remodeling wizards from what I've read so far.