diff --git a/cxx/mcc_fsm.h b/cxx/mcc_fsm.h
index 76a8bbc..a26a305 100644
--- a/cxx/mcc_fsm.h
+++ b/cxx/mcc_fsm.h
@@ -9,6 +9,7 @@
 #include <string_view>
 #include <typeindex>
 #include <unordered_map>
+#include <variant>
 #include "mcc_fsm_utils.h"
 
 
@@ -177,6 +178,7 @@ concept fsm_state_c =
 
 
 
+template <traits::fsm_state_c InitStateT>
 class MccFiniteStateMachine
 {
 public:
@@ -274,8 +276,70 @@ protected:
     //     };
     // }
 
-    template <typename StateTplT, typename>
+
+    // template<>
+
+
+    // merge N std::tuple types with filtering dublicates
+    // (NOTE: the first std::tuple type must contain unique types!!!)
+    template <typename... TplTs>
     struct merge_tuples_t;
+
+    template <>
+    struct merge_tuples_t<> {
+        using res_t = std::tuple<>;
+    };
+
+    template <typename TplT>
+    struct merge_tuples_t<TplT> {
+        using res_t = TplT;
+    };
+
+    template <typename TplT1, typename TplT2>
+    struct merge_tuples_t<TplT1, TplT2> {
+        using res_t = TplT1;
+    };
+
+    template <typename... T1, typename T2, typename... T2s>
+    struct merge_tuples_t<std::tuple<T1...>, std::tuple<T2, T2s...>>
+        : std::conditional_t<(std::same_as<T1, T2> || ...),
+                             merge_tuples_t<std::tuple<T1...>, std::tuple<T2s...>>,
+                             merge_tuples_t<std::tuple<T1..., T2>, std::tuple<T2s...>>> {
+    };
+
+    template <typename TplT1, typename TplT2, typename TplT3, typename... TplTs>
+    struct merge_tuples_t<TplT1, TplT2, TplT3, TplTs...>
+        : merge_tuples_t<typename merge_tuples_t<TplT1, TplT2>::res_t, TplT3, TplTs...> {
+    };
+
+    template <typename... TplTs>
+    using merge_tuples_res_t = typename merge_tuples_t<TplTs...>::res_t;
+
+    template <typename TplT>
+    struct variant_maker_t;
+
+    template <typename... Ts>
+    struct variant_maker_t<std::tuple<Ts...>> {
+        // using variant_t = std::variant<Ts*...>;
+        using variant_t = std::variant<std::reference_wrapper<Ts>...>;
+    };
+
+
+    template <typename... TplTs>
+    struct collect_states_t;
+
+    template <traits::fsm_state_c... StTs, typename... TplTs>
+    struct collect_states_t<std::tuple<StTs...>, TplTs...> {
+        using states_t = merge_tuples_res_t<std::tuple<StTs...>,
+                                            collect_states_t<typename StTs::transition_t::unique_states_t...>,
+                                            TplTs...>;
+    };
+
+
+    using states_t = typename collect_states_t<InitStateT>::states_t;
+
+    states_t _states;
+    typename variant_maker_t<states_t>::variant_t _currentStateVariant;
 };
 
 }  // namespace mcc::fsm