Section 681 ABGB links the inclusion of descendants who step in to the time of death. They must already have been conceived at that point. A later birth does not change the position where the statutory condition existed at death. A later family plan, however, does not satisfy this rule by itself.
For the review, record the date of death, the date of birth and the reliable information relevant to conception separately. In an international family, civil status records, medical documents or official records may be relevant. Which evidence is sufficient depends on the dispute and the authority dealing with it.
The timing condition is separate from the question whether the descendant takes the child’s place. Both points must be derived from the family line and the will. The article on grandchildren stepping into a predeceased child’s statutory line addresses a different situation where statutory succession, rather than this legacy, is the core issue.