I just wrote to someone,
Tell Alivia Wyatt says hi.
Am I missing a comma? It seems like there almost has to be one between the names. I find it a strange sentence to punctuate.
A comma would not make sense there, but using "that" in between Alivia and Wyatt would provide the separation that you are perceiving is needed.
This is a simple imperative statement, with the implied subject "you", the verb "tell", indirect object "Alivia", and direct object "Wyatt says hi".
In this case, one would not use a comma between the two names. Consider an equivalently structured sentence.
We would not write
as this would seem to say that I am the ball, and you should throw me.
Putting a comma between the two names would change the meaning, and would seem to say "Tell Alivia (something, probably specified in the previous sentence), because/and Wyatt says hi."
This is a more complicated issue than most simple commands, because the object is both an entire sentence on its own, and a direct quote.
If you're worried, you could put quotes round Wyatt says hi. Compare:
Come to that, you could also put quotes round hi, as it's reported speech.