diff --git a/osc/util/models.py b/osc/util/models.py
index d0493da8..d5f399be 100644
--- a/osc/util/models.py
+++ b/osc/util/models.py
@@ -379,6 +379,7 @@ class BaseModel(metaclass=ModelMeta):
         raise AttributeError(f"Setting attribute '{self.__class__.__name__}.{name}' is not allowed")
 
     def __init__(self, **kwargs):
+        self._allow_new_attributes = True
         self._defaults = {}  # field defaults cached in field.get()
         self._values = {}  # field values explicitly set after initializing the model
         self._parent = kwargs.pop("_parent", None)
@@ -447,6 +448,11 @@ class BaseModel(metaclass=ModelMeta):
 class XmlModel(BaseModel):
     XML_TAG = None
 
+    _apiurl: Optional[str] = Field(
+        exclude=True,
+        default=FromParent("_apiurl", fallback=None),
+    )
+
     def to_xml(self) -> ET.Element:
         xml_tag = None
 
@@ -466,6 +472,8 @@ class XmlModel(BaseModel):
         root = ET.Element(xml_tag)
 
         for field_name, field in self.__fields__.items():
+            if field.exclude:
+                continue
             xml_attribute = field.extra.get("xml_attribute", False)
             xml_set_tag = field.extra.get("xml_set_tag", False)
             xml_set_text = field.extra.get("xml_set_text", False)
@@ -517,20 +525,20 @@ class XmlModel(BaseModel):
         return root
 
     @classmethod
-    def from_string(cls, string: str) -> "XmlModel":
+    def from_string(cls, string: str, *, apiurl: Optional[str] = None) -> "XmlModel":
         """
         Instantiate model from string.
         """
         root = ET.fromstring(string)
-        return cls.from_xml(root)
+        return cls.from_xml(root, apiurl=apiurl)
 
     @classmethod
-    def from_file(cls, file: Union[str, typing.IO]) -> "XmlModel":
+    def from_file(cls, file: Union[str, typing.IO], *, apiurl: Optional[str] = None) -> "XmlModel":
         """
         Instantiate model from file.
         """
         root = ET.parse(file).getroot()
-        return cls.from_xml(root)
+        return cls.from_xml(root, apiurl=apiurl)
 
     def to_bytes(self) -> bytes:
         """
@@ -588,7 +596,7 @@ class XmlModel(BaseModel):
             parent.remove(node)
 
     @classmethod
-    def from_xml(cls, root: ET.Element):
+    def from_xml(cls, root: ET.Element, *, apiurl: Optional[str] = None):
         """
         Instantiate model from a XML root.
         """
@@ -668,7 +676,7 @@ class XmlModel(BaseModel):
                 for node in nodes:
                     if field.is_model_list:
                         klass = field.inner_type
-                        entry = klass.from_xml(node)
+                        entry = klass.from_xml(node, apiurl=apiurl)
 
                         # clear node as it was checked in from_xml() already
                         node.text = None
@@ -698,7 +706,7 @@ class XmlModel(BaseModel):
                 if node is None:
                     continue
                 klass = field.origin_type
-                kwargs[field_name] = klass.from_xml(node)
+                kwargs[field_name] = klass.from_xml(node, apiurl=apiurl)
 
                 # clear node as it was checked in from_xml() already
                 node.text = None
@@ -723,7 +731,7 @@ class XmlModel(BaseModel):
 
         cls._remove_processed_node(None, root)
 
-        obj = cls(**kwargs)
+        obj = cls(**kwargs, _apiurl=apiurl)
         obj.__dict__["_root"] = orig_root
         return obj
 
@@ -767,7 +775,7 @@ class XmlModel(BaseModel):
             while True:
                 run_editor(f.name)
                 try:
-                    edited_obj = self.__class__.from_file(f.name)
+                    edited_obj = self.__class__.from_file(f.name, apiurl=self._apiurl)
                     f.seek(0)
                     edited_data = f.read()
                     break
diff --git a/tests/test_models_xmlmodel.py b/tests/test_models_xmlmodel.py
index 36f3942b..665db5e2 100644
--- a/tests/test_models_xmlmodel.py
+++ b/tests/test_models_xmlmodel.py
@@ -1,3 +1,4 @@
+import io
 import textwrap
 import unittest
 
@@ -149,6 +150,41 @@ class TestXmlModel(unittest.TestCase):
         m = ParentModel.from_string(expected)
         self.assertEqual(m.to_string(), expected)
 
+    def test_apiurl(self):
+        class ChildModel(XmlModel):
+            XML_TAG = "child"
+            value: str = Field()
+
+        class ParentModel(XmlModel):
+            XML_TAG = "parent"
+            text: str = Field()
+            child: List[ChildModel] = Field(xml_wrapped=True, xml_name="children")
+
+        # serialize the model and load it with apiurl set
+        m = ParentModel(text="TEXT", child=[{"value": "FOO"}, {"value": "BAR"}])
+        xml = m.to_string()
+
+        apiurl = "https://api.example.com"
+
+        m = ParentModel.from_string(xml, apiurl=apiurl)
+        m.child.append({"value": "BAZ"})
+
+        self.assertEqual(m._apiurl, apiurl)
+        self.assertEqual(m.child[0]._apiurl, apiurl)
+        self.assertEqual(m.child[1]._apiurl, apiurl)
+        self.assertEqual(m.child[2]._apiurl, apiurl)
+
+        # test the same as above but with a file
+        f = io.StringIO(xml)
+
+        m = ParentModel.from_file(f, apiurl=apiurl)
+        m.child.append({"value": "BAZ"})
+
+        self.assertEqual(m._apiurl, apiurl)
+        self.assertEqual(m.child[0]._apiurl, apiurl)
+        self.assertEqual(m.child[1]._apiurl, apiurl)
+        self.assertEqual(m.child[2]._apiurl, apiurl)
+
 
 if __name__ == "__main__":
     unittest.main()