Simplify the following text for a Grade 7 native English-speaking person.
Original: They had four childrenâ '' Linda 's daughter Heather ( who was adopted by Paul ) , Mary , Stella and Jamesâ '' and remained married until Linda 's death from breast cancer in 1998 .
Simplified: She had a daughter , Heather , whom he adopted . McCartney and Linda had three more children together , named Mary , Stella and James .