 \rightarrow 0 \\ 0 \rightarrow {\mathbb{E}\text{xt}_{{\mathcal O}_{B'}}}^0(L_{\zeta'},{\mathcal O}_{B'}) \rightarrow {\mathbb{E}\text{xt}_{{\mathcal O}_{B}}}^0(L_\zeta,{\mathcal O}_B) \rightarrow 0 \\ 0 \rightarrow {\mathbb{E}\text{xt}_{{\mathcal O}_{B'}}}^0(L_{\zeta'},{\mathcal O}_{B'}) \rightarrow {\mathbb{E}\text{xt}_{{\mathcal O}_{B}}}^0(L_\zeta,{\mathcal O}_B) \rightarrow 0 \end{aligned}$$ So the Lie algebra of infinitesimal automorphisms of $\zeta'$ 