Hong Kong children can apply for their parents to settle down.

The specific conditions for Hong Kong children to apply for their parents' residence are as follows:

1. One of the husband and wife has settled in Hong Kong and separated for many years (according to the specific years of separation, the prescribed years of separation are different due to different local conditions).

2. Parents who have settled in Hong Kong are old and frail (aged 6 or above and have no children to take care of them in Hong Kong) and must be taken care of by mainland children (aged 18 or above).

3. The helpless elderly and children in the Mainland have to rely on their immediate family members and close relatives in Hong Kong.