{𝕜 : Type u_1} →
  [inst : NontriviallyNormedField 𝕜] →
    {E : Type u_2} →
      [inst_1 : NormedAddCommGroup E] →
        [inst_2 : NormedSpace 𝕜 E] →
          {E' : Type u_3} →
            [inst_3 : NormedAddCommGroup E'] →
              [inst_4 : NormedSpace 𝕜 E'] →
                {H : Type u_5} →
                  [inst_5 : TopologicalSpace H] →
                    {I : ModelWithCorners 𝕜 E H} →
                      {M : Type u_9} →
                        [inst_6 : TopologicalSpace M] →
                          [inst_7 : ChartedSpace H M] →
                            {n : WithTop ℕ∞} →
                              {M' : Type u_13} →
                                [inst_8 : TopologicalSpace M'] →
                                  [inst_9 : ChartedSpace H M'] →
                                    {N : Type u_15} →
                                      [inst_10 : TopologicalSpace N] →
                                        [inst_11 : ChartedSpace H N] →
                                          {J : ModelWithCorners 𝕜 E' H} →
                                            {N' : Type u_17} →
                                              [inst_12 : TopologicalSpace N'] →
                                                [inst_13 : ChartedSpace H N'] →
                                                  Diffeomorph I J M N n →
                                                    Diffeomorph I J M' N' n → Diffeomorph I J (M ⊕ M') (N ⊕ N') n