A previous civil suit filed by your mother concerning ancestral property was dismissed because the ancestral nature of the property couldn't be proven. While the principle of res judicata might prevent refiling the exact same case, experts suggest that if the original suit was for declaration only and not partition, a new suit for partition might still be maintainable. It's crucial to engage an experienced lawyer and provide all factual details to ensure the correct legal strategy is pursued, potentially even after the grandfather's demise.