Evolution of orbital inclinations between inner and outer orbits for hierarchical three-body systems obtained by integrating the secular equations for circular orbits. The system parameters are detailed in Table 1. We set the timescale of the disk dissipation (τ_d) to 1 × 10⁴ yr. In (a), the decay of host stellar oblateness is not considered. In (b), the oblateness of the host star decays due to its radius contraction: R_⋆ = R_⋆ (0)/(1 + t/τ_R⋆)^−1/3, where τ_R⋆ = 1 Myr. The temporal evolution of the equilibrium that dominates the planet’s evolution is depicted for each system. Notably, a jump in the equilibrium trajectory signifies an encounter with bifurcation B₂.