diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..fc3e0ec
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,4 @@
+[submodule "external/geomerge"]
+	path = external/geomerge
+	url = gitlab@git.sgai.uk:vincent_liu/geomerge.git
+	branch = main
diff --git a/external/geomerge b/external/geomerge
new file mode 160000
index 0000000..d8f60cd
--- /dev/null
+++ b/external/geomerge
@@ -0,0 +1 @@
+Subproject commit d8f60cdb15683f1036519003ea6c557dcee05776