diff --git a/python-lib/dku_utils.py b/python-lib/dku_utils.py
index 834b2af..eb170c4 100644
--- a/python-lib/dku_utils.py
+++ b/python-lib/dku_utils.py
@@ -1,6 +1,7 @@
 import json
 import copy
 import math
+from collections import defaultdict
 from jsonpath_ng.ext import parse
 from safe_logger import SafeLogger
 
@@ -9,7 +10,11 @@
 
 
 def get_dku_key_values(endpoint_query_string):
-    return {key_value.get("from"): key_value.get("to") for key_value in endpoint_query_string if key_value.get("from")}
+    result = defaultdict(list)
+    for kv in endpoint_query_string:
+        if kv.get('from') and kv.get('to'):
+            result[kv['from'].strip()].append(kv['to'].strip())
+    return dict(result)
 
 
 def get_endpoint_parameters(configuration):
@@ -98,15 +103,30 @@ def template_dict(dictionnary, **kwargs):
     return ret
 
 
-def format_template(template, **kwargs):
-    """ Replace {{keys}} elements in template with the matching value in the kwargs dictionnary"""
+def format_template(template, allow_list=False, **kwargs):
+    """
+    Replace {{key}} in template with the value(s) in the kwargs dictionnary.
+    If allow_list is False, list inputs will be joined into a comma-separated string (for headers).
+    If allow_list is True, lists will be returned as lists (for query params).
+    """
+    def replace_in(template):
+        formated = template
+        for key, value in kwargs.items():
+            formated = formated.replace(f"{{{{{key}}}}}", str(value))
+        return formated
     if template is None:
         return None
-    formated = template
-    for key in kwargs:
-        replacement = kwargs.get(key, "")
-        formated = formated.replace("{{{{{}}}}}".format(key), str(replacement))
-    return formated
+    elif isinstance(template, list):
+        replaced_list = [replace_in(item) for item in template]
+        if allow_list:
+            return replaced_list
+        else:
+            # To handle headers
+            return ", ".join(replaced_list)
+    elif isinstance(template, str):
+        return replace_in(template)
+    else:
+        return template
 
 
 def is_string(data):
diff --git a/python-lib/rest_api_client.py b/python-lib/rest_api_client.py
index 0b467ce..efaa2eb 100644
--- a/python-lib/rest_api_client.py
+++ b/python-lib/rest_api_client.py
@@ -46,7 +46,7 @@ def __init__(self, credential, secure_credentials, endpoint, custom_key_values={
         endpoint_headers = endpoint.get("endpoint_headers", "")
         self.endpoint_headers = self.get_params(endpoint_headers, self.presets_variables)
 
-        self.params = self.get_params(self.endpoint_query_string, self.presets_variables)
+        self.params = self.get_params(self.endpoint_query_string, self.presets_variables, True)
 
         self.extraction_key = endpoint.get("extraction_key", None)
 
@@ -195,11 +195,11 @@ def set_metadata(self, metadata_name, value):
         self.metadata["dku_{}".format(metadata_name)] = value
 
     @staticmethod
-    def get_params(endpoint_query_string, keywords):
+    def get_params(endpoint_query_string, keywords, allow_list=False):
         templated_query_string = get_dku_key_values(endpoint_query_string)
         ret = {}
         for key in templated_query_string:
-            ret.update({key: format_template(templated_query_string.get(key, ""), **keywords) or ""})
+            ret.update({key: format_template(templated_query_string.get(key, ""), allow_list=allow_list, **keywords) or ""})
         return ret
 
     def has_more_data(self):