diff --git a/simpeg_drivers-assets/uijson/joint_cross_gradient_inversion.ui.json b/simpeg_drivers-assets/uijson/joint_cross_gradient_inversion.ui.json
index 588f294d..c58b0d97 100644
--- a/simpeg_drivers-assets/uijson/joint_cross_gradient_inversion.ui.json
+++ b/simpeg_drivers-assets/uijson/joint_cross_gradient_inversion.ui.json
@@ -9,9 +9,7 @@
     "monitoring_directory": "",
     "workspace_geoh5": "",
     "inversion_type": "joint cross gradient",
-    "physical_property": [
-        ""
-    ],
+    "physical_property": "",
     "forward_only": false,
     "group_a": {
         "main": true,
diff --git a/simpeg_drivers/joint/driver.py b/simpeg_drivers/joint/driver.py
index fc90167a..927015ef 100644
--- a/simpeg_drivers/joint/driver.py
+++ b/simpeg_drivers/joint/driver.py
@@ -68,19 +68,14 @@ def drivers(self) -> list[InversionDriver] | None:
         """List of inversion drivers."""
         if self._drivers is None:
             drivers = []
-            physical_property = []
             # Create sub-drivers
             for group in self.params.groups:
                 _ = group.options  # Triggers something... otherwise ui_json is empty
                 group = group.copy(parent=self.params.out_group)
-
                 driver = simpeg_group_to_driver(group, self.workspace)
-
-                physical_property.append(driver.params.physical_property)
                 drivers.append(driver)
 
             self._drivers = drivers
-            self.params.physical_property = physical_property
 
         return self._drivers
 
diff --git a/simpeg_drivers/joint/joint_cross_gradient/options.py b/simpeg_drivers/joint/joint_cross_gradient/options.py
index 923429ed..3c79e150 100644
--- a/simpeg_drivers/joint/joint_cross_gradient/options.py
+++ b/simpeg_drivers/joint/joint_cross_gradient/options.py
@@ -38,8 +38,6 @@ class JointCrossGradientOptions(BaseJointOptions):
     )
 
     title: str = "Joint Cross Gradient Inversion"
-    physical_property: list[str] = [""]
-
     inversion_type: str = "joint cross gradient"
 
     mesh: Octree | None = None
diff --git a/simpeg_drivers/joint/options.py b/simpeg_drivers/joint/options.py
index 7e033bae..ee36906a 100644
--- a/simpeg_drivers/joint/options.py
+++ b/simpeg_drivers/joint/options.py
@@ -44,7 +44,7 @@ class BaseJointOptions(BaseData):
     run_command: str = "simpeg_drivers.driver"
     conda_environment: str = "simpeg-drivers"
     forward_only: bool = False
-    physical_property: list[str] = ["conductivity"]
+    physical_property: str | None = None
 
     group_a: SimPEGGroup
     group_a_multiplier: float = 1.0
@@ -101,6 +101,11 @@ class BaseJointOptions(BaseData):
     percentile: float = 95.0
     epsilon_cooling_factor: float = 1.2
 
+    n_workers: int | None = 1
+    n_threads: int | None = None
+    max_ram: float | None = None
+    performance_report: bool = False
+
     @property
     def groups(self) -> list[SimPEGGroup]:
         """List all active groups."""