diff --git a/DAPS/register_connector.sh b/DAPS/register_connector.sh
index 0a2b944..0f550ba 100755
--- a/DAPS/register_connector.sh
+++ b/DAPS/register_connector.sh
@@ -1,54 +1,59 @@
 #!/bin/sh
 
-if [ ! $# -ge 1 ] || [ ! $# -le 3 ]; then
-    echo "Usage: $0 NAME (SECURITY_PROFILE) (CERTFILE)"
-    exit 1
+# Validate the number of arguments (1 to 3)
+if [ "$#" -lt 1 ] || [ "$#" -gt 3 ]; then
+  echo "Usage: $0 NAME (SECURITY_PROFILE) (CERTFILE)"
+  exit 1
 fi
 
 CLIENT_NAME=$1
-
 CLIENT_SECURITY_PROFILE=$2
 [ -z "$CLIENT_SECURITY_PROFILE" ] && CLIENT_SECURITY_PROFILE="idsc:BASE_SECURITY_PROFILE"
-
 CLIENT_CERT="keys/$CLIENT_NAME.cert"
 
-SKI="$(openssl x509 -in "keys/${CLIENT_NAME}.cert" -noout -text | grep -A1 "Subject Key Identifier" | tail -n 1 | tr -d ' ')"
-AKI="$(openssl x509 -in "keys/${CLIENT_NAME}.cert" -noout -text | grep -A1 "Authority Key Identifier" | tail -n 1 | tr -d ' ')"
+# Extract SKI and AKI using openssl
+SKI="$(openssl x509 -in "$CLIENT_CERT" -noout -text | grep -A1 "Subject Key Identifier" | tail -n 1 | tr -d ' ')"
+AKI="$(openssl x509 -in "$CLIENT_CERT" -noout -text | grep -A1 "Authority Key Identifier" | tail -n 1 | tr -d ' ')"
 SUB='keyid'
 
-contains() {
-    string="$AKI"
-    substring="$SUB"
-    if test "${string#*$substring}" != "$string"
-    then
-        CLIENT_ID="$SKI:$AKI"    # $substring is in $string
-    else
-        CLIENT_ID="$SKI:keyid:$AKI"    # $substring is not in $string
-    fi
-}
-
-contains "$AKI" "$SUB"
+# Determine CLIENT_ID based on presence of 'keyid' in AKI
+if echo "$AKI" | grep -q "$SUB"; then
+  CLIENT_ID="$SKI:$AKI"
+else
+  CLIENT_ID="$SKI:keyid:$AKI"
+fi
 
 CLIENT_CERT_SHA="$(openssl x509 -in "$CLIENT_CERT" -noout -sha256 -fingerprint | tr '[:upper:]' '[:lower:]' | tr -d : | sed 's/.*=//')"
 
-cat >> config/clients.yml <<EOF
-- client_id: $CLIENT_ID
-  client_name: $CLIENT_NAME
-  grant_types: client_credentials
-  token_endpoint_auth_method: private_key_jwt
-  scope: idsc:IDS_CONNECTOR_ATTRIBUTES_ALL
-  attributes:
-  - key: idsc
-    value: IDS_CONNECTOR_ATTRIBUTES_ALL
-  - key: securityProfile
-    value: $CLIENT_SECURITY_PROFILE
-  - key: referringConnector
-    value: http://${CLIENT_NAME}.demo
-  - key: "@type"
-    value: ids:DatPayload
-  - key: "@context"
-    value: https://w3id.org/idsa/contexts/context.jsonld
-  - key: transportCertsSha256
-    value: $CLIENT_CERT_SHA
-  import_certfile: $CLIENT_CERT
-EOF
+# Check if a client with the same client_id or client_name exists
+CLIENT_EXISTS=$(yq eval '.[] | select(.client_id == "'"$CLIENT_ID"'" or .client_name == "'"$CLIENT_NAME"'")' config/clients.yml)
+
+if [ -n "$CLIENT_EXISTS" ]; then
+  echo "Client with ID $CLIENT_ID or name $CLIENT_NAME already exists. Updating the existing entry."
+
+  # Update client_id, client_name, and transportCertsSha256 for the exact matching entry
+  yq eval -i '
+    map(
+      select(.client_id == "'"$CLIENT_ID"'" or .client_name == "'"$CLIENT_NAME"'") |= 
+      (.client_id = "'"$CLIENT_ID"'" | 
+       .client_name = "'"$CLIENT_NAME"'" | 
+       (.attributes[] | select(.key == "transportCertsSha256").value) = "'"$CLIENT_CERT_SHA"'")
+    )
+  ' config/clients.yml
+
+  echo "Client entry updated successfully."
+  exit 0
+fi
+
+# If the client does not exist, append the new client entry
+echo "Adding new client entry to config/clients.yml."
+
+# Ensure the file ends with a newline
+if [ -n "$(tail -c 1 config/clients.yml)" ] && [ "$(tail -c 1 config/clients.yml)" != $'\n' ]; then
+  echo >>config/clients.yml
+fi
+
+# Append the new client entry
+yq eval -i '. += [{"client_id": "'"$CLIENT_ID"'", "client_name": "'"$CLIENT_NAME"'", "grant_types": "client_credentials", "token_endpoint_auth_method": "private_key_jwt", "scope": "idsc:IDS_CONNECTOR_ATTRIBUTES_ALL", "attributes": [{"key": "idsc", "value": "IDS_CONNECTOR_ATTRIBUTES_ALL"}, {"key": "securityProfile", "value": "'"$CLIENT_SECURITY_PROFILE"'"}, {"key": "referringConnector", "value": "http://'"${CLIENT_NAME}"'.demo"}, {"key": "@type", "value": "ids:DatPayload"}, {"key": "@context", "value": "https://w3id.org/idsa/contexts/context.jsonld"}, {"key": "transportCertsSha256", "value": "'"$CLIENT_CERT_SHA"'"}], "import_certfile": "'"$CLIENT_CERT"'"}]' config/clients.yml
+
+echo "Client entry added successfully."