Of the human challenges facing Hong Kong this year, the handling of thousands of immigrant children who have right of abode is among the most daunting. Every mainland child with a Hong Kong father has the automatic right to live in the Special Administrative Region, but for the sake of social stability, and for the good of the young migrants themselves, there has to be a planned and orderly system of admission. Ideally, the arrangements to cope with the influx should have been worked out long ago. Nobody has any clear idea of the numbers involved, the age groups, or the family background - or of how many school and kindergarten places will be required. Faced with this essentially humanitarian issue, the outgoing and incoming administrations have come together to work out ways to absorb the influx of children in the most efficient way possible, without overwhelming the system. This is a very welcome breakthrough in an otherwise regrettable impasse. It gives government officials the chance to work with the incoming administration, without involving the thorny issues which have stood in the way of forward planning in other areas. With goodwill on all sides, a solid working framework can be drawn up to smooth out the problems. Yesterday's agreement to co-operate should set a model for co-operation in handling other similar social and human issues, and should not remain in isolated example of good sense.