China Multi entry Visa

I am a New Zealand citizen living in New Zealand and plan to Visit Beijing for about 7 weeks, starting end of April.

I have a sibling working in Beijing with a China permanent residence visa so I will apply for a Family Reunion visa (3-month visa)

Mid May we would like to visit Hong Kong, Shenzhen and Guangzhou for about 10 days before returning to Beijing.

Rather than flying to either Shenzhen or Guangzhou, it appears that the cheapest airfare option is to first fly to Hong Kong (we would like to spend 3 days there) then catch to the high-speed train to Shenzhen and then onto Guangzhou.

Our plan is that after visiting Guangzhou we would return to Shenzhen then back to Hong Kong to spend 2 more days there then fly back to Beijing.

My question is - Seeing that I would be entering China Mainland 3 times would I need to apply for a multiple-entry visa or would just a 3 month single China entry visa cover this?

The 3 Mainland entries would be.

(1) Original entry to Beijing
(2) Fly to Hong Kong - enter Shenzhen
(3) Return to Hong Kong - Fly to Beijing