diff --git a/src/gui_qt/data/container.py b/src/gui_qt/data/container.py
index 940ac62..fd268d8 100644
--- a/src/gui_qt/data/container.py
+++ b/src/gui_qt/data/container.py
@@ -45,6 +45,7 @@ class ExperimentContainer(QtCore.QObject):
         self.actions = {}
         self._update_actions()
 
+    @plot_update
     def _init_plot(self):
         raise NotImplementedError
 
@@ -528,17 +529,17 @@ class PointContainer(ExperimentContainer):
                 line_kwargs['style'] = LineStyle.No
                 sym_kwargs['symbol'] = next(PointContainer.symbols)
 
-        self.plot_real = PlotItem(x=self._data.x, y=self._data.y, name=self.name,
+        self.plot_real = PlotItem(x=self.x, y=self.y, name=self.name,
                                   symbol=None, pen=None, connect='finite')
 
         self.setSymbol(mode='real', **sym_kwargs)
         self.setLine(mode='real', **line_kwargs)
 
         if sym_kwargs['symbol'] != SymbolStyle.No:
-            self.plot_error = ErrorBars(x=self._data.x, y=self._data.y, top=self._data.y_err, bottom=self._data.y_err,
+            self.plot_error = ErrorBars(x=self.x, y=self.y, top=self.y_err, bottom=self.y_err,
                                         pen=mkPen({'color': self.plot_real.symbolcolor.rgb()}))
         else:
-            self.plot_error = ErrorBars(x=self._data.x, y=self._data.y, top=self._data.y_err, bottom=self._data.y_err,
+            self.plot_error = ErrorBars(x=self.x, y=self.y, top=self.y_err, bottom=self.y_err,
                                         pen=mkPen({'color': self.plot_real.linecolor.rgb()}))
 
 
@@ -561,12 +562,12 @@ class FitContainer(ExperimentContainer):
         if isinstance(color, BaseColor):
             color = color.rgb()
 
-        self.plot_real = PlotItem(x=self._data.x, y=self._data.y.real, name=self.name,
+        self.plot_real = PlotItem(x=self.x, y=self.y.real, name=self.name,
                                   pen=mkPen({'color': color}),
                                   connect='finite', symbol=None)
 
         if np.iscomplexobj(self._data.y):
-            self.plot_imag = PlotItem(x=self._data.x, y=self._data.y.imag, name=self.name,
+            self.plot_imag = PlotItem(x=self.x, y=self.y.imag, name=self.name,
                                       pen=mkPen({'color': color}),
                                       connect='finite', symbol=None)
 
@@ -599,9 +600,9 @@ class SignalContainer(ExperimentContainer):
         self._init_plot(symbol=symbol, **kwargs)
 
     def _init_plot(self, **kwargs):
-        self.plot_real = PlotItem(x=self._data.x, y=self._data.y.real, name=self.name,
+        self.plot_real = PlotItem(x=self.x, y=self.y.real, name=self.name,
                                   symbol=None, pen=None, connect='finite')
-        self.plot_imag = PlotItem(x=self._data.x, y=self._data.y.imag, name=self.name,
+        self.plot_imag = PlotItem(x=self.x, y=self.y.imag, name=self.name,
                                   symbol=None, pen=None, connect='finite')
 
         color = kwargs.get('color', None)
diff --git a/src/gui_qt/main/management.py b/src/gui_qt/main/management.py
index a85e4d1..9655835 100644
--- a/src/gui_qt/main/management.py
+++ b/src/gui_qt/main/management.py
@@ -343,7 +343,7 @@ class UpperManagement(QtCore.QObject):
             if joined is None:
                 joined = data_i.copy()
             else:
-                joined.append(data_i.x, data_i.y, data_i.y_err)
+                joined.append(data_i.data.x, data_i.data.y, y_err=data_i.data.y_err, mask=data_i.data.mask)
 
             name_set.add(data_i.name)
             group_set.add(data_i.group)
diff --git a/src/nmreval/data/points.py b/src/nmreval/data/points.py
index c2169ff..671142d 100644
--- a/src/nmreval/data/points.py
+++ b/src/nmreval/data/points.py
@@ -497,8 +497,11 @@ class Points:
 
         return self
 
-    def append(self, x: ArrayLike, y: ArrayLike, y_err: ArrayLike = None):
-        x, y, y_err, mask = self._prepare_xy(x, y, y_err)
+    def append(self, x: ArrayLike, y: ArrayLike, y_err: ArrayLike = None, mask: ArrayLike = None):
+        if mask is None:
+            x, y, y_err, mask = self._prepare_xy(x, y, y_err)
+        else:
+            x, y, y_err, _ = self._prepare_xy(x, y, y_err)
 
         self._x = np.r_[self._x, x]
         self._y = np.r_[self._y, y]