Wills/Estates, Probate issues....?

In California, to re~open probate on a Will/Estate based on newly discovered evidence(fraud) & it was discovered by an heir that was mentioned in the will, but heir was not notified of ANY court proceedings in the past, can she petition to reopen it after more then 10 years has gone by? Also heir is on SSI Disability for being a slow learner/plus other issues but NOT crazy or anything, just a slow learner that makes her not learn as fast as others that's all. What should she do? Thanks~ : )