will bring my family to hongkong this april 17-20. what kind of clothes do we have to bring?

Currently, it is hard to tell the exact weather for your visiting time, but only a general information can be told based on the previous records.
The average temperature during that time is around 22 to 26C. Sometimes, it will rain, but neither consective nor heavy.
Since there is no extreme weather, there is no special tips for the senior people and kids. In general, the local people are kind to the kids and senior people. It is windy for that city and you need to care about this issue.