One of the most difficult challenges of being a foster parent is providing a stable, loving environment for a child knowing that he or she will one day move on to a new home. It might be for six weeks; it might be for six years. Wendy Ng Woon-ying takes out a photograph album she started 18 months ago, when Donald, three, came to live with her, her husband and her 11-year-old son. She is philosophical about her temporarily extended family. Donald is waiting to be placed with a suitable adoptive family but, until then, is likely to remain with the Ngs. 'I know he will leave one day, but it is more important to give him good care so he is a happy boy before he joins his future family,' said Mrs Ng. She has already mentally prepared herself for that and regularly reminds herself Donald will have to leave at some point. 'The separation will be hard but if he goes to a good family it will be best for him.' With spare time on her hands, space in her home and a willing husband and son, Mrs Ng was keen to foster children. She already had the confidence from years of experience raising her own son. When she met Donald for the first time she was sure that, by providing a stable environment and exposing him to new things, she could help him develop. He is her first foster child and is very much a part of the family. She treats him as she does her biological son, providing a nurturing environment and discipline when it is needed. One of her biggest rewards as a foster mother has been seeing Donald develop from a passive child who hated even to travel on a bus into a lively, active child. He had also increased her circle of friends, Mrs Ng said, and enriched her family's life. 'He is very sociable. He brings a lot of happiness ... he makes us all laugh.' What can you do? At the end of November last year, 667 children were in foster care. There are six non-governmental foster care agencies in Hong Kong. If you would like to find out more about becoming a foster parent, contact the Central Foster Care Service at the Social Welfare Department on 28524596.