Complex sentence: In 1998, when she achieved the milestone of becoming the world's oldest person when 117 year old Marie-Louise Febronie Meilleur of Quebec died, her family members told her of her new found fame.
Split into simpler sentences: In 1998, she is thought to have became the world's oldest person when 117 year old Marie-Louise Febronie Meilleur of Quebec died. When her family members told her of her new found fame.