Marco and Rick notice Cathy becoming broody around Phoebe Bright (Simone Robertson) and she decides that she wants another child. Her behaviour results in her admitting that she had a daughter and adopted her. Arena told Josephine Monroe from "Inside Soap" that her confession hurts Marco the most because he always believed himself to be Cathy's oldest child. The Alessi's decide that it is best forget about it, but Marco cannot. Arena explained that "Marco becomes very secretive" and starts searching for his sister. Rick pleads with Marco not to fearing it will destroy the family, but he is stubborn and continues the search. Arena added "Marco's really pissed off that they never told him and he's especially hurt that his mum kept a secret from him because his mum is his best friend." The adoption agency locate her, now living as Lindsay Steiner (Jane Longhurst). She refuses to return contact with Marco. Monroe noted that Marco is "deeply disappointed" because he has expected to have an "instant rapport" with his long lost sister. But Lindsay later begins to follow Marco around. When he discovers her identity he decides to introduce her to Cathy and Benito. Arena billed the scenes as "lots of shouting and slamming of doors" which he enjoyed playing. He credited the scenes as his favourite and working so closely with Ballantyne and Spartels created his best acting work.