diff --git a/docs/changes.md b/docs/changes.md
index b805d613..9ec2f452 100644
--- a/docs/changes.md
+++ b/docs/changes.md
@@ -44,6 +44,7 @@ Changes that will break existing code and need active thinking and work to adapt
 tests/issues/issue_1146.py
 examples/advanced/spline_draw2.py
 examples/volumetric/isosurfaces2.py
+examples/pyplot/fit_curve2.py
 ```
 
 
diff --git a/docs/examples_db.js b/docs/examples_db.js
index 4d501a66..7374c048 100755
--- a/docs/examples_db.js
+++ b/docs/examples_db.js
@@ -1453,7 +1453,7 @@ vedo_example_db =
         imgsrc: 'images/pyplot/fit_erf.png',
     },
     {
-        pyname: 'fit_curve',
+        pyname: 'fit_curve1',
         kbd   : '',
         categ : 'plotting',
         short : 'fit data w/ error bars',
diff --git a/examples/pyplot/fit_curve.py b/examples/pyplot/fit_curve1.py
similarity index 100%
rename from examples/pyplot/fit_curve.py
rename to examples/pyplot/fit_curve1.py
diff --git a/examples/pyplot/fit_curve2.py b/examples/pyplot/fit_curve2.py
new file mode 100644
index 00000000..a35855c5
--- /dev/null
+++ b/examples/pyplot/fit_curve2.py
@@ -0,0 +1,44 @@
+"""Create slider that changes the value of the k parameter in the function."""
+import numpy as np
+from vedo.pyplot import plot
+from vedo import settings, Line, Text2D, Plotter
+
+
+settings.default_font = "Brachium"
+settings.remember_last_figure_format = True
+
+
+def func(x, h, a, x0, k):
+    return h + a * (x-x0) * np.sin((x-x0)**2 / k)
+
+
+def callback(w, e):
+    y = func(xdata, *true_params[:3], slider.value)
+    res = np.sum((ydata - y)**2 / 100)
+    txt2d.text(f"Residuals: {res:.3f}")
+    # remove previous fit line and insert the new one
+    line = Line(np.c_[xdata, y], c="green4", lw=3)
+    p.remove(p[2]).insert(line)
+
+
+true_params = [20, 2, 8, 3]
+xdata = np.linspace(3, 10, 100)
+ydata_true = func(xdata, *true_params)
+ydata = np.random.normal(ydata_true, 3, 100)
+
+p = plot(
+    xdata,
+    ydata,
+    "o", 
+    mc="blue2", 
+    title="f = h + a*(x-x_0 )*sin((x-x_0 )**2 /k)",
+    label="Data",
+)
+p += plot(xdata, ydata_true, "-g", lw=2, label="Fit")
+p.add_legend(pos="top-right")
+
+txt2d = Text2D(pos="bottom-left", bg='yellow5', s=1.2)
+
+plt = Plotter(size=(900, 650))
+slider = plt.add_slider(callback, 1, 5, value=3, title="k-value")
+plt.show(p, txt2d, __doc__, zoom=1.3, mode="2d")
diff --git a/vedo/assembly.py b/vedo/assembly.py
index 832578f2..5d70132f 100644
--- a/vedo/assembly.py
+++ b/vedo/assembly.py
@@ -133,9 +133,7 @@ def __str__(self):
         return out.rstrip() + "\x1b[0m"
 
     def __iadd__(self, obj):
-        """
-        Add an object to the group
-        """
+        """Add an object to the group."""
         if not vedo.utils.is_sequence(obj):
             obj = [obj]
         for a in obj:
@@ -144,7 +142,30 @@ def __iadd__(self, obj):
                     self.AddPart(a)
                 except TypeError:
                     self.AddPart(a.actor)
-                    self.objcects.append(a)
+                    self.objects.append(a)
+        return self
+
+    def __isub__(self, obj):
+        """Remove an object to the group."""
+        if not vedo.utils.is_sequence(obj):
+            obj = [obj]
+        for a in obj:
+            if a:
+                try:
+                    self.RemovePart(a)
+                except TypeError:
+                    self.RemovePart(a.actor)
+                    self.objects.append(a)
+        return self
+
+    def add(self, obj):
+        """Add an object to the group."""
+        self.__iadd__(obj)
+        return self
+    
+    def remove(self, obj):
+        """Remove an object to the group."""
+        self.__isub__(obj)
         return self
 
     def _unpack(self):
@@ -402,6 +423,36 @@ def unpack_group(scalarbar):
             self.pipeline = vedo.utils.OperationNode("add mesh", parents=[self, obj], c="#f08080")
         return self
 
+    def __isub__(self, obj):
+        """
+        Remove an object to the assembly.
+        """
+        if not vedo.utils.is_sequence(obj):
+            obj = [obj]
+        for a in obj:
+            if a:
+                try:
+                    self.RemovePart(a)
+                    self.objects.remove(a)
+                except TypeError:
+                    self.RemovePart(a.actor)
+                    self.objects.remove(a)
+        return self
+
+    def add(self, obj):
+        """
+        Add an object to the assembly.
+        """
+        self.__add__(obj)
+        return self
+    
+    def remove(self, obj):
+        """
+        Remove an object to the assembly.
+        """
+        self.__isub__(obj)
+        return self
+
     def __contains__(self, obj):
         """Allows to use `in` to check if an object is in the `Assembly`."""
         return obj in self.objects
diff --git a/vedo/version.py b/vedo/version.py
index 80206f35..0771df0c 100644
--- a/vedo/version.py
+++ b/vedo/version.py
@@ -1 +1 @@
-_version = '2024.5.2+dev10'
+_version = '2024.5.2+dev11'