https://www.biologyonline.com/dictionary/life
Many things have definitions that don't work at the edges. The terms were created without regard for those edges, or even awareness in some cases. Lets consider another: What is life?
Bacteria--certainly.
Viruses--this can be argued either way.
Prions--I have never seen them seriously considered life, yet they are an infectious agent.
Computer viruses--again, this can be argued either way.
And, what is a unique life?
At fertilization? It can split into two or more identical twins after that point. Two (or theoretically more, but I've never heard of a case) fertilized eggs can also combine to form a chimera.