Fly from Christchurch of New Zealand to Phnom Penh, Cambodia

We're flying from Christchurch of NZ to Phnom Penh of Cambodia end of next week and stopover in Guangzhou, China for 3.15 hours on our way to Cambodia and 6 hours on return way. So I'm wondering we can use TWOV to stopover in Guangzhou on both ways? We have multiples nationality.