Help for my clickable weakaura

[Nico1420]

Hello everyone, I created a weakaura that allows me to launch a BoP on my "focus" when I receive a whisp "bop" by a big button that appears on my screen.
I would like to perfect this and replace my focus with the person who threw the whisp at me.

currently it's like this

aura_env.wplayer = nil
aura_env.button = CreateFrame("Button", "buffButton", aura_env.region, "SecureActionButtonTemplate", BackdropTemplateMixin and "BackdropTemplate")

aura_env.button:SetAllPoints()
aura_env.button:SetAttribute("unit", "focus")
aura_env.button:SetAttribute("type","spell")

aura_env.auraID = 318038
aura_env.button:SetAttribute("spell", 10278)
aura_env.BuffLevel = 8


I put in bold and underlined what I need to change to be able to cast on the person who whisp me... because it's complicated in raid to plan his focus in advance