Can a will made in 1997, probated in 2014 be challenged

Can a will made in 1997, probated in 2014, without giving court notice to other inheritors be challenged, if other inheritors hold a registered will of 2012, but not probated? Christian mother made will in 1997 gave a son 1/3 of her share, but changed the will giving all 7 children in 2012 an equal share of her 1/3 share of property inherited. Mother died in 2014, but son probated 1997 will in 2014 claiming 1/3 share of mother. Which WILL holds more value? Can probated will of 1997 be challenged, as court notice not issued to other inheritors,except paper ad, missed by them, so unchallenged.