family with 2 chidren (8 -10) travelling from kuala lumpur to pechino and after 4 days to hong kong

Yes, if Beijing is your only stop in Mainland China.

Pechino = Beijing here.

Hong Kong is a Chinese territory but it is considered as a different country by mainland China authority.

Your tickets have 3 differents countries. 1. Malaysia 2. the 144-hour visa for Pechino 3. a direct flight to Hong Kong.

But! No other landing in wherever in China. It means that you can't go from Pechino via a 2-hour transit in Shanghai then Hong Kong.

All transits inside another mainland China airport being accepted need a full visa.