Let $Y$ be a smooth complex projective curve of genus two,
$X$ a Galois cover of degree two of $Y$ and $K$ the canonical
divisor of $X$. Let $i$ be the involution of $X$ over $Y$.
Can one find two points $P$ and $P'$ on $X$ such
that

 $$ 2P' = 3P + 3i(P) - K$$

and neither $P'$ nor its conjugate (note that $X$ is hyperelliptic)
is equal to $P$ or $Q$?

(Thanks to abx for his answer to my previous question).