  By applying the lantern relation substitutions to the positive relation of
the genus two Lefschetz fibration over $\mathbb{S}^{2}$. We show that $K3\#2
\overline{\mathbb{CP}}{}^{2}$ can be rationally blown down along seven disjoint
copies of the configuration $C_2$. We compute the Seiberg-Witten invariant of
the resulting symplectic 4-manifolds, and show that they are symplectically
minimal. We also investigate how these exotic smooth 4-manifolds constructed
via lantern relation substitution method are fiber sum decomposable.
Furthermore by considering all the possible decompositions for each of our
decomposable exotic examples, we will find out that there is a uniquely
decomposing genus 2 Lefschetz fibration which is not a self sum of the same
fibration up to diffeomorphism on the indecomposable summands.
