will it be possible to get china visa upon arrival @ Shenzen or @ zhuhai custom port ? Thai passport

I and my family will accompany with my 76 year-old grandma who holds chinese passport.

we plan to visit both places from Hongkong and Macau, we will fly to Hongkong first, then travel to both Shenzen and Zhuhai.

Please answer, we make this trip because it is a last trip and last requirement of my grandma to visit her home country. And the reason that we visit Hongkong first because one of my grandma's son (my uncle) lives in Hongkong.