diff --git a/pm4py/algo/discovery/powl/inductive/variants/im_tree.py b/pm4py/algo/discovery/powl/inductive/variants/im_tree.py
index 56f35fc78..8e8e9de2d 100644
--- a/pm4py/algo/discovery/powl/inductive/variants/im_tree.py
+++ b/pm4py/algo/discovery/powl/inductive/variants/im_tree.py
@@ -97,8 +97,6 @@ def fall_through(self, obj: T, parameters: Optional[Dict[str, Any]] = None) -> T
     def _recurse(self, powl: POWL, objs: List[T], parameters: Optional[Dict[str, Any]] = None):
         children = [self.apply(obj, parameters=parameters) for obj in objs]
         if isinstance(powl, StrictPartialOrder):
-            if isinstance(powl, Sequence):
-                return Sequence(children)
             powl_new = StrictPartialOrder(children)
             for i, j in combinations(range(len(powl.children)), 2):
                 if powl.order.is_edge_id(i, j):
diff --git a/pm4py/objects/powl/obj.py b/pm4py/objects/powl/obj.py
index ceb6684fb..fff8ccde4 100644
--- a/pm4py/objects/powl/obj.py
+++ b/pm4py/objects/powl/obj.py
@@ -336,9 +336,9 @@ def merge_with_children(child0, child1):
                 s_child = child.simplify()
                 if isinstance(s_child, OperatorPOWL) and s_child.operator is Operator.XOR:
                     for node in s_child.children:
-                        new_children.append(node)
+                        new_children.append(node.simplify())
                 else:
                     new_children.append(s_child)
             return OperatorPOWL(Operator.XOR, [child for child in new_children])
         else:
-            return OperatorPOWL(self.operator, [child for child in self.children])
+            return OperatorPOWL(self.operator, [child.simplify() for child in self.children])
diff --git a/requirements_stable.txt b/requirements_stable.txt
index 4fc3bb8d7..321cd977f 100644
--- a/requirements_stable.txt
+++ b/requirements_stable.txt
@@ -2,17 +2,17 @@ colorama==0.4.6
 contourpy==1.2.0
 cycler==0.12.1
 deprecation==2.1.0
-fonttools==4.46.0
+fonttools==4.47.0
 graphviz==0.20.1
 intervaltree==3.1.0
 kiwisolver==1.4.5
-lxml==4.9.3
+lxml==5.0.0
 matplotlib==3.8.2
 networkx==3.2.1
 numpy==1.26.2
 packaging==23.2
 pandas==2.1.4
-Pillow==10.1.0
+Pillow==10.2.0
 pydotplus==2.0.2
 pyparsing==3.1.1
 python-dateutil==2.8.2
@@ -22,4 +22,4 @@ six==1.16.0
 sortedcontainers==2.4.0
 StringDist==1.0.9
 tqdm==4.66.1
-tzdata==2023.3
+tzdata==2023.4