diff --git a/multigrid/examples/double.json b/multigrid/examples/double.json
new file mode 100644
index 0000000..93775af
--- /dev/null
+++ b/multigrid/examples/double.json
@@ -0,0 +1,39 @@
+{
+    "grids": {
+        "default": {
+            "x": { "linspace": { "start": -5, "end": 5, "steps": 100 } },
+            "operators": {
+                "xi": "upwind9",
+                "eta": "upwind9h2"
+            },
+            "boundary_conditions": {
+                "east": "vortex",
+                "west": "vortex"
+            }
+        },
+        "grid0": {
+            "y": { "linspace": { "start": 0, "end": 5, "steps": 50, "h2": true } },
+            "boundary_conditions": {
+                "south": { "neighbour": "grid1" },
+                "north": { "neighbour": "grid1" }
+            }
+        },
+        "grid1": {
+            "y": { "linspace": { "start": -5, "end": 0, "steps": 50, "h2": true } },
+            "boundary_conditions": {
+                "south": { "neighbour": "grid0" },
+                "north": { "neighbour": "grid0" }
+            }
+        }
+    },
+    "integration_time": 2.0,
+    "vortex": {
+        "vortices": [{
+            "x0": -1.0,
+            "y0": 0.0,
+            "rstar": 0.5,
+            "eps": 1.0
+        }],
+        "mach": 0.5
+    }
+}
diff --git a/multigrid/src/parsing.rs b/multigrid/src/parsing.rs
index 347b250..ede3309 100644
--- a/multigrid/src/parsing.rs
+++ b/multigrid/src/parsing.rs
@@ -233,9 +233,12 @@ impl Configuration {
                     (op::Upwind9, op::Upwind9h2) => {
                         Right(Box::new((&Upwind9, &Upwind9h2)) as Box<dyn UpwindOperator2d>)
                     }
+                    (op::Upwind9h2, op::Upwind9) => {
+                        Right(Box::new((&Upwind9h2, &Upwind9)) as Box<dyn UpwindOperator2d>)
+                    }
                     (op::Sbp4, op::Sbp4) => Left(Box::new(SBP4) as Box<dyn SbpOperator2d>),
                     (op::Sbp8, op::Sbp8) => Left(Box::new(SBP8) as Box<dyn SbpOperator2d>),
-                    _ => todo!(),
+                    _ => todo!("Combination {:?}, {:?} not implemented", eta, xi),
                 }
             })
             .collect();
@@ -244,9 +247,12 @@ impl Configuration {
             .iter()
             .enumerate()
             .map(|(i, (_name, g))| {
+                let default_bc = default.boundary_conditions.clone().unwrap_or_default();
                 g.boundary_conditions
                     .clone()
-                    .unwrap_or_else(|| default.boundary_conditions.clone().unwrap_or_default())
+                    .unwrap_or_default()
+                    .zip(default_bc)
+                    .map(|(bc, fallback)| bc.or(fallback))
                     .map(|bc| match bc {
                         None | Some(BoundaryType::Vortex) => {
                             euler::BoundaryCharacteristic::Vortex(self.vortex.clone())
diff --git a/sbp/src/utils.rs b/sbp/src/utils.rs
index 06e49e7..426ab4c 100644
--- a/sbp/src/utils.rs
+++ b/sbp/src/utils.rs
@@ -45,6 +45,25 @@ impl<T> Direction<T> {
             east: f(self.east),
         }
     }
+    pub fn zip<U>(self, other: Direction<U>) -> Direction<(T, U)> {
+        Direction {
+            north: (self.north, other.north),
+            south: (self.south, other.south),
+            west: (self.west, other.west),
+            east: (self.east, other.east),
+        }
+    }
+}
+
+impl<T> Direction<Option<T>> {
+    pub fn unwrap_or(self, other: Direction<T>) -> Direction<T> {
+        Direction {
+            north: self.north.unwrap_or(other.north),
+            south: self.south.unwrap_or(other.south),
+            west: self.west.unwrap_or(other.west),
+            east: self.east.unwrap_or(other.east),
+        }
+    }
 }
 
 impl<T> Direction<T> {