diff --git a/finite_state_machine/draw_state_diagram.py b/finite_state_machine/draw_state_diagram.py
index 0d12c19..2f02ae1 100644
--- a/finite_state_machine/draw_state_diagram.py
+++ b/finite_state_machine/draw_state_diagram.py
@@ -26,7 +26,6 @@ def generate_state_diagram_markdown(cls, initial_state):
 
     https://mermaid-js.github.io/mermaid/diagrams-and-syntax-and-examples/stateDiagram.html
     """
-
     class_fns = inspect.getmembers(cls, predicate=inspect.isfunction)
     state_transitions: List[Transition] = [
         func.__fsm for name, func in class_fns if hasattr(func, "__fsm")
diff --git a/finite_state_machine/state_machine.py b/finite_state_machine/state_machine.py
index ede63e6..2bd2704 100644
--- a/finite_state_machine/state_machine.py
+++ b/finite_state_machine/state_machine.py
@@ -1,6 +1,7 @@
 import functools
 import types
 from typing import NamedTuple, Union
+import inspect
 
 from .exceptions import ConditionsNotMet, InvalidStartState
 
@@ -45,7 +46,38 @@ def transition(source, target, conditions=None, on_error=None):
             raise ValueError("on_error needs to be a bool, int or string")
 
     def transition_decorator(func):
-        func.__fsm = Transition(func.__name__, source, target, conditions, on_error)
+        mems = inspect.getmembers(func)
+        state_machine_instance = [
+            mem[1]["StateMachine"] for mem in mems if mem[0] == "__globals__"
+        ][0]
+        func.__fsm = Transition(
+            name=func.__name__,
+            source=source,
+            target=target,
+            conditions=conditions,
+            on_error=on_error,
+        )
+
+        # creating and/or adding items to __fsm attribute
+        if hasattr(state_machine_instance, "__fsm"):
+            if isinstance(source, list):
+                for src in source:
+                    if src in state_machine_instance.__fsm:
+                        state_machine_instance.__fsm[src].append(target)
+                    else:
+                        state_machine_instance.__fsm[src] = [target]
+            else:
+                if source in state_machine_instance.__fsm:
+                    state_machine_instance.__fsm[src].append(target)
+                else:
+                    state_machine_instance.__fsm[src] = [target]
+        else:
+            if isinstance(source, list):
+                state_machine_instance.__fsm = {}
+                for src in source:
+                    state_machine_instance.__fsm[src] = [target]
+            else:
+                state_machine_instance.__fsm.source = [target]
 
         @functools.wraps(func)
         def _wrapper(*args, **kwargs):