diff --git a/crossmnt b/crossmnt
new file mode 100755
index 0000000..81ac1fe
--- /dev/null
+++ b/crossmnt
@@ -0,0 +1,63 @@
+#!/usr/bin/env python3
+"""
+Add crossmnt to TrueNAS NFS exports for child dataset visibility.
+
+Usage: fix-nfs-crossmnt.py /mnt/pool/dataset
+
+Setup:
+  1. scp fix-nfs-crossmnt.py root@truenas.local:/root/
+  2. chmod +x /root/fix-nfs-crossmnt.py
+  3. Test: /root/fix-nfs-crossmnt.py /mnt/pool/dataset
+  4. Add cron job: TrueNAS UI > System > Advanced > Cron Jobs
+     Command: /root/fix-nfs-crossmnt.py /mnt/pool/dataset
+     Schedule: */5 * * * *
+"""
+
+import re
+import subprocess
+import sys
+from pathlib import Path
+
+EXPORTS_FILE = Path("/etc/exports")
+
+
+def main():
+    if len(sys.argv) != 2:
+        print(f"Usage: {sys.argv[0]} /mnt/pool/dataset", file=sys.stderr)
+        return 1
+
+    export_path = sys.argv[1]
+    content = EXPORTS_FILE.read_text()
+
+    if f'"{export_path}"' not in content:
+        print(f"ERROR: {export_path} not found in {EXPORTS_FILE}", file=sys.stderr)
+        return 1
+
+    lines = content.splitlines()
+    result = []
+    in_block = False
+    modified = False
+
+    for line in lines:
+        if f'"{export_path}"' in line:
+            in_block = True
+        elif line.startswith('"'):
+            in_block = False
+
+        if in_block and line[:1] in (" ", "\t") and "crossmnt" not in line:
+            line = re.sub(r"\)(\\\s*)?$", r",crossmnt)\1", line)
+            modified = True
+
+        result.append(line)
+
+    if not modified:
+        return 0  # Already applied
+
+    EXPORTS_FILE.write_text("\n".join(result) + "\n")
+    subprocess.run(["exportfs", "-ra"], check=True)
+    print(f"Added crossmnt to {export_path}")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())