The short answer is don't try this!
A loan file that should be approved is stuck in an underwriting "black hole" in which all communication is cutoff and cannot get an answer yeah or nay, weather they will approve the mortgage insurance or not. A borrowers loan (with many migitating risk factors) is basically being held hostage by the underwriter for well over a week when a decision should have been made within 24 hours.
If you don't want to add any additional stress to your financed purchase transactions go with FHA financing if you're client cannot put at least 20% down! UPDATE--FHA will allow income from a non-occupant coborrower for loan qualification. Some MI companies, however, will not and will not provide MI. Yet another reason to use FHA and avoid the private MI issue altogether!