$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
7.15
\begin{equation} \begin{gathered}\label{equation:fiberwise-relative-Kan-general} \xymatrix@R =50pt@C=50pt{ \operatorname{\mathcal{K}}{\coprod }_{\operatorname{\mathcal{K}}_0} (\operatorname{\mathcal{K}}_0 \star _{\operatorname{\mathcal{C}}_0} \operatorname{\mathcal{C}}_0) \ar [r]^-{F_0} \ar [d] & \operatorname{\mathcal{D}}\ar [d]^{U} \\ \operatorname{\mathcal{K}}\star _{\operatorname{\mathcal{C}}} \operatorname{\mathcal{C}}\ar [r] \ar@ {-->}[ur] & \operatorname{\mathcal{E}}} \end{gathered} \end{equation}