Question about potential macro (or something else)

Hello, lovely Hunters!

I have a question and I hope somebody knows how to do this. I would like to put Arcane Shot and Kill Shot into one button, using Kill Shot if it is up, and Arcane Shot otherwise. I can’t think of a way to do this with macros, but I am hoping that somebody knows of a way to do this, and I am willing to install an add-on (or multiple) if they can make this possible. (As long as they are allowed!)

Thank you for your time.

Its not possible with a macro.

A /castsequence macro would would attempt the first option (KS) if it fails then it would be stuck until that option is available, only then would it move to the second spell.

Not possible.

Read this.

https://us.forums.blizzard.com/en/wow/t/macros-essential-information/21139