Do I need a return visa to China if Im coming from visting Hong Kong

Hi. We are arriving at Baiyun Guangzhou from Australia. Will be in Guangzhou for one night and then will leave the next morning to go to Hong Kong (via train). Will be visting in Hong Kong for 4 days. Will return to Guangzhou via train and go straight to Baiyun Airport for flight to USA.

Please can you advise/assist with which visas are required. Two adults and one child travelling.

Many thanks