Utilize the input text as a context reference, choose the right relationship between St George Bank and Westpac from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Mrs Kelly was chief executive and managing director of St George Bank from 2002 to 2007 and CEO of Westpac from 2008 until early this year, overseeing a merger of the two banks in 2008.

Answer: parent_organization