diff --git a/src/NoPELib/player_settings.py b/src/NoPELib/player_settings.py
index 8d22f79..ab4d8fb 100644
--- a/src/NoPELib/player_settings.py
+++ b/src/NoPELib/player_settings.py
@@ -237,6 +237,9 @@ class ExpansionsManager:
         Container of the expansions to try making available
     activeExpansions: dict of Expansion
         Container of the relevent expansions
+    
+    Methods:
+    expansionPlayersChanged
     """
     defaultExpansionConfig = {"players": (), "types": ()}
     keysConvert2Tuple = ("players", "types")
@@ -251,6 +254,7 @@ class ExpansionsManager:
         """
         # Create the attributes
         self.playersManager = playersManager
+        self._playersLookUp = {}
         self._cfg = playersManager.config["expansions"]
         if includedExpansions is not None:
             self._includedExpansions = tuple(includedExpansions)
@@ -306,7 +310,7 @@ class ExpansionsManager:
 
     def _listPossiblyValidExpansions(self):
         """
-        List expansions that are included, defined in expansionsLib and are available
+        List expansions that are: included, defined in expansionsLib and available
         to at least one active player.
         """
         activePlayers = set(self.playersManager.keys())
@@ -319,14 +323,20 @@ class ExpansionsManager:
 
     def _createExpansion(self, expansionID):
         try:
+            # Create the expansion
             expansion = getattr(expansionsLib, expansionID)(expansionID, self)
+            # Update the lookup
+            for player in self._getPlayersFillMissing(expansionID):
+                self._playersLookUp[player].append(expansionID)
+            return expansion
         except Exception as e:
-            print(f"Could not initilise {expansionID} because of traceback:")
-            print(e)
-        else:
-            self._activeExpansions[expansionID] = expansion
+            return e
 
     def _removeExpansion(self, expansionID):
+        # Update the lookup
+        for player in self._getPlayersFillMissing(expansionID):
+            self._playersLookUp[player].pop(expansionID)
+        # Remove the expansion
         expansion = self._activeExpansions.pop(expansionID)
         expansion.close()
         del expansion
@@ -346,7 +356,11 @@ class ExpansionsManager:
         # Add the new expansions
         expansionsToAdd = possiblyValidExpansions.difference(previousExpansions)
         for expansionID in expansionsToAdd:
-            self._createExpansion(expansionID)
+            creation_out = self._createExpansion(expansionID)
+            if isinstance(creation_out, expansionsLib.Expansion):
+                self._activeExpansions[expansionID] = creation_out
+            else:
+                print(creation_out)
 
     def _activePlayerAdded(self, playerName):
         # Find the expansions that are to be created
@@ -358,7 +372,11 @@ class ExpansionsManager:
         ]
         # Create the expansions
         for expansionID in filteredAddition:
-            self._createExpansion(expansionID)
+            creation_out = self._createExpansion(expansionID)
+            if isinstance(creation_out, expansionsLib.Expansion):
+                self._activeExpansions[expansionID] = creation_out
+            else:
+                print(creation_out)
 
     def _activePlayerRemoved(self, playerName):
         # Find the expansions that are to be removed
@@ -373,15 +391,55 @@ class ExpansionsManager:
     def _errorOccured(self, expansionID):
         self._removeExpansion(expansionID)
 
-    def expansionPlayersChanged(self, expansionID):
+    def expansionPlayersChanged(self, expansionID, newPlayers):
+        """
+        Method that allows changing the assigned players of an expansion.
+
+        Arguments:
+            expansionID (str): 
+            newPlayers (tuple of str): 
+        """
+        # Save the change
+        previousPlayers = self._cfg[expansionID]["players"]
+        self._cfg[expansionID]["players"] = tuple(newPlayers)
+        # Check the state of the expansion
         expansionIsActive = expansionID in self._activeExpansions
         activePlayers = set(self.playersManager.keys())
         expansionHasNoPlayers = self._getPlayersFillMissing(expansionID).isdisjoint(activePlayers)
         expansionDefined = hasattr(expansionsLib, expansionID)
+        # Update the activation status
+        activeChanged = False
         if expansionIsActive and expansionHasNoPlayers:
             self._removeExpansion(expansionID)
+            activeChanged = True
         elif (not expansionIsActive) and (not expansionHasNoPlayers) and expansionDefined:
-            self._createExpansion(expansionID)
+            creation_out = self._createExpansion(expansionID)
+            if isinstance(creation_out, expansionsLib.Expansion):
+                self._activeExpansions[expansionID] = creation_out
+                activeChanged = True
+            elif isinstance(creation_out, Exception):
+                print(creation_out)
+        # Update the inverse lookup
+        if not activeChanged:
+            removedPlayers = set(previousPlayers).difference(newPlayers)
+            addedPlayers = set(newPlayers).difference(previousPlayers)
+            for playerName in removedPlayers:
+                self._playersLookUp[playerName].pop(expansionID)
+            for playerName in addedPlayers:
+                self._playersLookUp[playerName].append(expansionID)
+    
+    def lookupPlayer(self, playerName):
+        """
+        Get a tuple of all expansions available to a player.
+
+        Arguments:
+            playerName (str): Name of the player
+        
+        Returns:
+            expansionsID (tuple of str): ID of the expansions available to the
+                player
+        """
+        return tuple(self._playersLookUp[playerName])
 
 
 if __name__ == "__main__":