Thank you to all those who answered this problem, which is not as straightforward as it may seem.
John and Chadwick in Year 7 at Coleridge Community College sent in these solutions:
John	Chadwick
Kenny and Bon from Our Lady's School in Welwyn Garden City found these arrangements:
Kenny	Bon
Children from the Challenge Club at Lodgefields Primary School, Crewe have found more arrangements:
Emily	Ian
Christopher	David and Daniel
Maybe there are other possibilities?