diff --git a/db/migrate/20251114183203_ensure_an_identit_can_only_have_one_user_in_an_account.rb b/db/migrate/20251114183203_ensure_an_identit_can_only_have_one_user_in_an_account.rb
new file mode 100644
index 000000000..091ae9f35
--- /dev/null
+++ b/db/migrate/20251114183203_ensure_an_identit_can_only_have_one_user_in_an_account.rb
@@ -0,0 +1,5 @@
+class EnsureAnIdentitCanOnlyHaveOneUserInAnAccount < ActiveRecord::Migration[8.2]
+  def change
+    add_index :users, [:account_id, :identity_id], unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 0b20106de..62114dd17 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.2].define(version: 2025_11_14_084325) do
+ActiveRecord::Schema[8.2].define(version: 2025_11_14_183203) do
   create_table "accesses", id: :uuid, charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.datetime "accessed_at"
     t.uuid "account_id", null: false
@@ -692,6 +692,7 @@ ActiveRecord::Schema[8.2].define(version: 2025_11_14_084325) do
     t.string "name", null: false
     t.string "role", default: "member", null: false
     t.datetime "updated_at", null: false
+    t.index ["account_id", "identity_id"], name: "index_users_on_account_id_and_identity_id", unique: true
     t.index ["account_id", "role"], name: "index_users_on_account_id_and_role"
     t.index ["identity_id"], name: "index_users_on_identity_id"
   end
diff --git a/script/import-sqlite-database.rb b/script/import-sqlite-database.rb
index 38d48304b..719123198 100755
--- a/script/import-sqlite-database.rb
+++ b/script/import-sqlite-database.rb
@@ -128,6 +128,7 @@ class Import
             }
           )
           @tenant = @account.external_account_id
+          @admin = @account.users.find_by(role: :admin)
         end
 
         old_join_code = import.account_join_codes.sole
@@ -153,13 +154,17 @@ class Import
             new_identity = Identity.find_or_create_by!(email_address: membership.identity.email_address)
           end
 
-          new_user = User.create!(
-            account: account,
-            identity: new_identity,
-            name: old_user.name,
-            role: old_user.role,
-            active: old_user.active,
-          )
+          new_user = if new_identity == @admin.identity
+            @admin
+          else
+            User.create!(
+              account: account,
+              identity: new_identity,
+              name: old_user.name,
+              role: old_user.role,
+              active: old_user.active,
+            )
+          end
 
           old_settings = old_user.settings
           if old_settings