And you want to "build her credit" so you can borrow money in her name and rip somebody else off. Wow.
If you are working and she is staying home, what would be the upside to your NOT working and letting the credit build in her name, other than that there may already be some bad credit, unpaid debts and such in your name?
You obviously do not understand the cross matching and checks that are in place if one works for a covered employer using any social security number. The unemployment system, the social security system, the IRS, all of these entities share information and their systems busily cross match all social security numbers for anyone reporting wages on taxes, payroll records, etc. This will happen long before you have "built up credit" for her anywhere.
And do you think they won't notice you're suddenly Mary Doe and not John?