Complex sentence: The McManus Galleries in Dundee today exhibit Joy's substantial commissions to paint Grace Darling and her father William, who had become Victorian heroes after rescuing sailors from the distressed "Forfarshire" paddle steamer.
Split into simpler sentences: The McManus Galleries in Dundee today exhibit Joy's substantial commissions to paint Grace Darling and her father. Grace and William Darling had become Victorian heroes after rescuing sailors from the distressed "Forfarshire" paddle steamer.