Questions About Old Structural Repair

cincycontractor

Homeowner wants me to replace this porch keeping the existing roof and not doing any more to the support below than necessary. Has anyone ever seen this type of structural repair. It looks like it was originally set in place to handle the weight of the retaining walls. However I believe over time the ground dropped a few inches on the right (obviously there's no poured piers or similar support under the slab) and that side is sagging now. I don't think its going anywhere now but even if I do repair this how do I get everything else back to level? I'm thinking support the roof , repair structure , build new porch , then jack the second floor up to where I need it (just a few inches , the gutter slope makes it look worse than it is) off my new structure.
Any suggestions or comments would be helpful.
Thanks
Justin

jdbdesign

Is the right side of the porch settling? looks that way from the pic. What's supporting the center of the porch over garage doors? looks like the joists are running the opposite way.