 No matter what you do to fix this, if you don't have professional direction on this, it could potentially impact the value of your house. If you've got some serious cracks like that and you're trying to address that and make sure it doesn't happen again, a structural engineer is the one that should be designing that repair because when you go to sell the house, once the repair is done, you want to be able to prove to the potential buyer that the repair was done under professional supervision and not just the combination of a bunch of contractors' opinions of what they think ought to be done.