Well, to determine if it's a zombie crossover fanfic, you need to look at whether it features characters or storylines from multiple zombie-themed works. Sometimes, it might just be inspired by multiple sources without being a full crossover.
It could be. It depends on the specific plot and characters involved. If there are elements from different zombie-related universes combined, then yes.
Chapter 540, "I am the Young Master's Nanny", is the clearest early answer because it turns Zhao Lang's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Compared to Lu Long's impulsiveness, Lu Hu seemed much more composed.
Chapter 147, "Jiang Li, We Are Going to Meet Again", is the clearest early answer because it turns Wenwen's situation into a concrete plot event. Early on, Xiao Xueyi nodded in agreement after listening.. By the end, Only Jiang Li glanced back at Director Sun, and then took out her own....
Chapter 183, "Sacrifice Oneself, Break Them Up!", is the clearest early answer because it turns President Shang's situation into a concrete plot event.
Chapter 284, "You'll Never Get Rid of Me!", is the clearest early answer because it turns Du Qinglian's situation into a concrete plot event.
Chapter 477, "Brother Pig, Don't Be Afraid", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on Alright then, everyone come over and eat while it's still hot." Jiang...
Chapter 486, "So It's All Set Up, Right? Then She Will Set Up Too!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from Hearing Jiang Li's words, the audience in the live stream was also...
Chapter 464, "Is it Lingzhi?!", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li's calculations were indeed correct.
Chapter 150, "Has She Been Cursed?!", is the clearest early answer because it turns Cursed's situation into a concrete plot event. The chapter gives readers a real answer by opening on Upon hearing the first part of Jiang Li's words, Zhang Cheng...
Chapter 528, "Cursed", is the clearest early answer because it turns Shang Group's situation into a concrete plot event. It opens with The netizens almost unanimously started to sympathize with Jiang... and closes on The current balance is 89!] Su Yinwan: "...." She was tired..
Chapter 345, "Audition: She Couldn't Have Gotten in Through Backdoor Connections, Could She?", is the clearest early answer because it turns Have Gotten's situation into a concrete plot event.