Let $\pi: P \to M$ be a smooth principal right $G$-bundle over a connected smooth manifold $M$, and let $\omega$ be a connection on $P$. Let $x,y \in M$, let $p \in P_x := \pi^{-1}(\{x\})$, and let $q \in P_y := \pi^{-1}(\{y\})$. Choose a piecewise smooth path $\alpha: [0,1] \to M$ with $\alpha(0)=x$ and $\alpha(1)=y$. Since the right action of $G$ on $P_y$ is free and transitive, there is a unique element $h \in G$ such that

\begin{align*} \operatorname{PT}_{\alpha}(p)=q h. \end{align*}

Then

\begin{align*} \operatorname{Hol}_q(\omega)=h \operatorname{Hol}_p(\omega) h^{-1}. \end{align*}