Complex sentence: From the age of 12, she has been active in supporting the Children's Miracle Network, which does fundraising for children's hospitals, e.g., through the Celebration Broadcast, a televised fundraising event.
Split into simpler sentences: From the age of 12, she has been active in supporting the Children's Miracle Network, which does fundraising for children's hospitals. She has participated in the Celebration Broadcast, a televised fundraising event.