diff --git a/CHANGELOG.md b/CHANGELOG.md
index f981cc4..11e9bc4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## latest
 
+- Added support to load multiple pyFANS builds in the same Python session [#142](https://github.com/DataAnalyticsEngineering/FANS/pull/142)
 - Bugfix: mem-leak while reading microstructure and added wider CMake support [#140](https://github.com/DataAnalyticsEngineering/FANS/pull/140)
 - Added MPI communicator abstraction [#139](https://github.com/DataAnalyticsEngineering/FANS/pull/139)
 
diff --git a/README.md b/README.md
index 90b6a6a..7586692 100644
--- a/README.md
+++ b/README.md
@@ -185,14 +185,15 @@ cd ../test
 
 **Build options:**
 
-| CMake Option | Description | Default |
-| -------------- | ------------- | --------- |
-| `CMAKE_BUILD_TYPE` | Build type: `Debug`, `Release`, `RelWithDebInfo` | `NONE` |
-| `CMAKE_INTERPROCEDURAL_OPTIMIZATION` | Enable link-time optimization (LTO) | `ON` (if supported) |
-| `FANS_BUILD_STATIC` | Build static library | `OFF` |
-| `CMAKE_INSTALL_PREFIX` | Installation directory | System default |
-| `FANS_LIBRARY_FOR_MICRO_MANAGER` | Build Python bindings using Pybind11 (needed) | `OFF` |
-| `FANS_ENABLE_SANITIZERS` | Enable runtime sanitizers (AddressSanitizer and LeakSanitizer) for memory debugging | `OFF` |
+| CMake Option                         | Description                                                                                           | Default             |
+|--------------------------------------|-------------------------------------------------------------------------------------------------------|---------------------|
+| `CMAKE_BUILD_TYPE`                   | Build type: `Debug`, `Release`, `RelWithDebInfo`                                                      | `NONE`              |
+| `CMAKE_INTERPROCEDURAL_OPTIMIZATION` | Enable link-time optimization (LTO)                                                                   | `ON` (if supported) |
+| `FANS_BUILD_STATIC`                  | Build static library                                                                                  | `OFF`               |
+| `CMAKE_INSTALL_PREFIX`               | Installation directory                                                                                | System default      |
+| `FANS_LIBRARY_FOR_MICRO_MANAGER`     | Build Python bindings (pyFANS) using Pybind11 (needed)                                                | `OFF`               |
+| `FANS_ENABLE_SANITIZERS`             | Enable runtime sanitizers (AddressSanitizer and LeakSanitizer) for memory debugging                   | `OFF`               |
+| `MicroSimulationSuffix`              | Numeric suffix for pyFANS registration within Pybind11. Required when loading multiple pyFANS builds. | `NONE`              |
 
 ---
 
diff --git a/pyfans/CMakeLists.txt b/pyfans/CMakeLists.txt
index 47882af..978e79e 100644
--- a/pyfans/CMakeLists.txt
+++ b/pyfans/CMakeLists.txt
@@ -2,6 +2,36 @@ pybind11_add_module(PyFANS micro.hpp micro.cpp)
 target_include_directories(PyFANS PRIVATE ${HDF5_INCLUDE_DIRS} ${FFTW3_INCLUDE_DIRS})
 target_link_libraries(PyFANS PRIVATE FANS::FANS)
 
+# Optional integer option (empty by default)
+set(MicroSimulationSuffix "" CACHE STRING "Optional numeric variant suffix")
+
+# Validate: must be empty or integer
+if(MicroSimulationSuffix STREQUAL "")
+    set(CLASS_NAME MicroSimulation)
+    set(INPUT_NAME input.json)
+    set(CONFIG_NAME pyfans-config.json)
+    set(MODULE_NAME PyFANS)
+else()
+    if(NOT MicroSimulationSuffix MATCHES "^[0-9]+$")
+        message(FATAL_ERROR "MicroSimulationSuffix must be an integer, got '${MicroSimulationSuffix}'")
+    endif()
+
+    set(CLASS_NAME MicroSimulation${MicroSimulationSuffix})
+    set(INPUT_NAME input${MicroSimulationSuffix}.json)
+    set(CONFIG_NAME pyfans-config${MicroSimulationSuffix}.json)
+    set(MODULE_NAME PyFANS${MicroSimulationSuffix})
+    message("Using MicroSimulationSuffix: ${MicroSimulationSuffix}")
+endif()
+
+# Add compile definitions
+target_compile_definitions(PyFANS PRIVATE
+        PyFANS_CLASS_NAME=${CLASS_NAME}
+        PyFANS_CLASS_NAME_STR="${CLASS_NAME}"
+        PyFANS_INPUT_NAME="${INPUT_NAME}"
+        PyFANS_CONFIG_NAME="${CONFIG_NAME}"
+        PyFANS_MODULE_NAME=${MODULE_NAME}
+)
+
 add_custom_command(
         TARGET PyFANS
         POST_BUILD
diff --git a/pyfans/micro.cpp b/pyfans/micro.cpp
index 2e9f7b9..ff72c3e 100644
--- a/pyfans/micro.cpp
+++ b/pyfans/micro.cpp
@@ -44,7 +44,7 @@ PyFANSConfig load_config(const std::string &file_path)
     return config;
 }
 
-MicroSimulation::MicroSimulation(int sim_id, const std::string &input_file, const std::string &config_file)
+PyFANS_CLASS_NAME::PyFANS_CLASS_NAME(int sim_id, const std::string &input_file, const std::string &config_file)
 {
     // initialize fftw mpi
     fftw_mpi_init();
@@ -66,7 +66,7 @@ MicroSimulation::MicroSimulation(int sim_id, const std::string &input_file, cons
     solver     = createSolver<3, 6>(reader, matmanager);
 }
 
-py::dict MicroSimulation::solve(py::dict macro_data, double dt)
+py::dict PyFANS_CLASS_NAME::solve(py::dict macro_data, double dt)
 {
     // Time step value dt is not used currently, but is available for future use
 
@@ -113,12 +113,12 @@ py::dict MicroSimulation::solve(py::dict macro_data, double dt)
     return micro_write_data;
 }
 
-PYBIND11_MODULE(PyFANS, m)
+PYBIND11_MODULE(PyFANS_MODULE_NAME, m)
 {
     // optional docstring
     m.doc() = "FANS for Micro Manager";
 
-    py::class_<MicroSimulation>(m, "MicroSimulation")
+    py::class_<PyFANS_CLASS_NAME>(m, PyFANS_CLASS_NAME_STR)
         .def(py::init<int>())
-        .def("solve", &MicroSimulation::solve);
+        .def("solve", &PyFANS_CLASS_NAME::solve);
 }
diff --git a/pyfans/micro.hpp b/pyfans/micro.hpp
index 2dbe418..d91c84d 100644
--- a/pyfans/micro.hpp
+++ b/pyfans/micro.hpp
@@ -17,9 +17,25 @@
 
 namespace py = pybind11;
 
-class MicroSimulation {
+#ifndef PyFANS_CLASS_NAME
+#define PyFANS_CLASS_NAME MicroSimulation
+#endif
+#ifndef PyFANS_CLASS_NAME_STR
+#define PyFANS_CLASS_NAME_STR "MicroSimulation"
+#endif
+#ifndef PyFANS_INPUT_NAME
+#define PyFANS_INPUT_NAME "input.json"
+#endif
+#ifndef PyFANS_CONFIG_NAME
+#define PyFANS_CONFIG_NAME "pyfans-config.json"
+#endif
+#ifndef PyFANS_MODULE_NAME
+#define PyFANS_MODULE_NAME PyFANS
+#endif
+
+class PyFANS_CLASS_NAME {
   public:
-    MicroSimulation(int sim_id, const std::string &input_file = "input.json", const std::string &config_file = "pyfans-config.json");
+    PyFANS_CLASS_NAME(int sim_id, const std::string &input_file = PyFANS_INPUT_NAME, const std::string &config_file = PyFANS_CONFIG_NAME);
     py::dict solve(py::dict macro_write_data, double dt);
 
   private: