MFS in CA - how can my client avoid penalties if ex does not file all his community income?

My client separated from spouse in June 2009 and filed for divorce shortly thereafter. Divorce will not be final until the end of March 2010. She will be filing MFS for 2009 because her ex refuses to file MFJ. He agreed to send me all his tax info which I'll use to calculate my client's 25% share of his income (1/2 of his income for 1/2 the year).  Then she'll report 75% of her income.  But my question is, what if when he files, he refuses to report his 25% share of her income?  Will she be liable for taxes on that amount?  Am I better off just reporting her income and letting him report his own?   I'm just trying to protect my client.