diff --git a/flopy/mf6/data/mfstructure.py b/flopy/mf6/data/mfstructure.py
index 34a78a780e..047f2697f8 100644
--- a/flopy/mf6/data/mfstructure.py
+++ b/flopy/mf6/data/mfstructure.py
@@ -13,6 +13,8 @@
 
 import numpy as np
 
+from flopy.mf6.inspect import get_solution_packages
+
 from ..mfbase import PackageContainer, StructException
 
 numeric_index_text = (
@@ -2461,6 +2463,11 @@ def tag_read_as_arrays(self):
                     package_struct.read_as_arrays = True
 
 
+def _get_solution_packages():
+    pkgs = get_solution_packages()
+    return {k.lower().replace("modflow", ""): "*" for k in pkgs.keys()}
+
+
 class MFStructure:
     """
     Singleton class for accessing the contents of the json structure file
@@ -2492,7 +2499,9 @@ def __new__(cls, internal_request=False, load_from_dfn_files=False):
             cls._instance.sim_struct = None
             cls._instance.dimension_dict = {}
             cls._instance.load_from_dfn_files = load_from_dfn_files
-            cls._instance.flopy_dict = {}
+            cls._instance.flopy_dict = {
+                "solution_packages": _get_solution_packages()
+            }
 
             # Read metadata from file
             cls._instance.valid = cls._instance.__load_structure()
@@ -2509,9 +2518,6 @@ def __load_structure(self):
         # set up structure classes
         self.sim_struct = MFSimulationStructure()
 
-        # initialize flopy dict keys
-        MFStructure().flopy_dict["solution_packages"] = {}
-
         if self.load_from_dfn_files:
             mf_dfn = Dfn()
             dfn_files = mf_dfn.get_file_list()
@@ -2542,44 +2548,12 @@ def __load_structure(self):
                                     "parameter_name": line_lst[6],
                                 }
                                 MFStructure().flopy_dict[line_lst[3]] = sp_dict
-                            elif line_lst[2] == "solution_package":
-                                MFStructure().flopy_dict["solution_packages"][
-                                    line_lst[3]
-                                ] = line_lst[4:]
-            if len(MFStructure().flopy_dict["solution_packages"]) == 0:
-                MFStructure().flopy_dict["solution_packages"]["ims"] = ["*"]
-                warnings.warn(
-                    "Package definition files (dfn) do not define a solution "
-                    "package.  This can happen if your dfn files are out of "
-                    "sync.  Auto-loaded default IMS solution package metadata."
-                    "  In the future auto-loading default metadata will be "
-                    "deprecated.",
-                    DeprecationWarning,
-                )
-            # process each file
             for file in dfn_files:
                 self.sim_struct.process_dfn(DfnFile(file))
             self.sim_struct.tag_read_as_arrays()
         else:
-            package_list = PackageContainer.package_list()
-            for package in package_list:
-                # process header
-                for entry in package.dfn[0][1:]:
-                    if (
-                        isinstance(entry, list)
-                        and entry[0] == "solution_package"
-                    ):
-                        MFStructure().flopy_dict["solution_packages"][
-                            package.package_abbr
-                        ] = entry[1:]
-                # process each package
+            for package in PackageContainer.package_list():
                 self.sim_struct.process_dfn(DfnPackage(package))
             self.sim_struct.tag_read_as_arrays()
 
-        return True
-
-    @staticmethod
-    def __valid_line(line):
-        if len(line.strip()) > 1 and line[0] != "#":
-            return True
-        return False
+        return True
\ No newline at end of file
diff --git a/flopy/mf6/inspect.py b/flopy/mf6/inspect.py
new file mode 100644
index 0000000000..525fdff5ba
--- /dev/null
+++ b/flopy/mf6/inspect.py
@@ -0,0 +1,46 @@
+from collections.abc import Mapping
+
+
+def get_classes(predicate=None) -> Mapping[str, type]:
+    import flopy.mf6.modflow as modflow
+    from flopy.utils.inspect import get_classes as _get_classes
+
+    return _get_classes(
+        modflow,
+        lambda cls: hasattr(cls, "dfn") and (predicate(cls) if predicate else True),
+    )
+
+
+def get_multi_packages() -> Mapping[str, type]:
+    def _filter(cls):
+        return (
+            len(cls.dfn) > 0
+            and len(cls.dfn[0]) >= 2
+            and cls.dfn[0][1] == "multi-package"
+        )
+
+    return get_classes(_filter)
+
+
+def get_solution_packages() -> Mapping[str, type]:
+    def _filter(cls):
+        return (
+            len(cls.dfn) > 0
+            and len(cls.dfn[0]) >= 2
+            and len(cls.dfn[0][1]) > 0
+            and cls.dfn[0][1][0] == "solution_package"
+        )
+
+    return get_classes(_filter)
+
+
+def get_sub_packages() -> Mapping[str, type]:
+    def _filter(cls):
+        return (
+            len(cls.dfn) > 0
+            and len(cls.dfn[0]) >= 2
+            and len(cls.dfn[0][1]) > 0
+            and cls.dfn[0][1][0] == "subpackage"
+        )
+    
+    return get_classes(_filter)
diff --git a/flopy/utils/inspect.py b/flopy/utils/inspect.py
new file mode 100644
index 0000000000..1ded3b83e9
--- /dev/null
+++ b/flopy/utils/inspect.py
@@ -0,0 +1,8 @@
+import inspect
+from collections.abc import Mapping
+
+
+def get_classes(module, predicate=None) -> Mapping[str, type]:
+    """Find classes in a module which satisfy a predicate."""
+    classes = inspect.getmembers(module, inspect.isclass)
+    return {name: cls for name, cls in classes if predicate(cls)}