Complex sentence: While driving Lisa to ballet practice, Marge--who is proud of having a ballerina as a daughter--starts glowing about how she sees herself in Lisa and Lisa begins to suspect that Marge is living out her dream through her.
Split into simpler sentences: While driving Lisa to ballet practice, Marge, who is proud of having a ballerina as a daughter, starts glowing about how she sees herself in Lisa. Lisa soon begins to suspect that Marge is living out her dream through her.