Don't know what your return has on it and don't know what your spouse has as income besides compensation, if anything, or deductions that would qualify for entry on Schedule A if you itemized. the earned income exclusion has a limit and any unearned income she has would be taxed by the US. so it may not be as simple as manually filling out a 1040-X, 2555 and the letter. certain other lines might change such as the tax computation because you are going from MFS to Joint.
