A claim for inheritance recovery must be filed within 3 years from the date on which one knew that one's right to inheritance was infringed,
or within 10 years from the date of the infringement on one's right to inheritance even if one did not know the fact.
Therefore, if the deceased died 30 years ago, and the heirs did not know that their inheritance rights were violated during that period,
or even if they did know, if they did not take any action, they cannot file a claim for inheritance recovery.
In fact, there are many cases in which people remain silent even if they know to some extent
that their inheritance rights have been violated due to concerns about family disputes.
Even if you decide to seek the right to inheritance 10 years after the date of the infringement,
there are often cases where you cannot find the right due to the expiration of the period.