diff --git a/htdocs/core/class/html.formprojet.class.php b/htdocs/core/class/html.formprojet.class.php
index 1112d34d13f..6c2b5600917 100644
--- a/htdocs/core/class/html.formprojet.class.php
+++ b/htdocs/core/class/html.formprojet.class.php
@@ -446,7 +446,7 @@ class FormProjets
 	 *    Build a HTML select list of element of same thirdparty to suggest to link them to project
 	 *
 	 *    @param	string		$table_element		Table of the element to update
-	 *    @param	int			$socid				If of thirdparty to use as filter
+	 *    @param	string		$socid				If of thirdparty to use as filter or 'id1,id2,...'
 	 *    @param	string		$morecss			More CSS
 	 *    @param    int         $limitonstatus      Add filters to limit length of list to opened status (for example to avoid ERR_RESPONSE_HEADERS_TOO_BIG on project/element.php page). TODO To implement
 	 *    @return	int|string						The HTML select list of element or '' if nothing or -1 if KO
@@ -502,7 +502,11 @@ class FormProjets
 		$sql.= " FROM ".MAIN_DB_PREFIX.$table_element." as t";
 		if ($linkedtothirdparty) $sql.=", ".MAIN_DB_PREFIX."societe as s";
 		$sql.= " WHERE ".$projectkey." is null";
-		if (! empty($socid) && $linkedtothirdparty) $sql.= " AND t.fk_soc=".$socid;
+		if (! empty($socid) && $linkedtothirdparty)
+		{
+		    if (is_numeric($socid)) $sql.= " AND t.fk_soc=".$socid;
+		    else $sql.= " AND t.fk_soc IN (".$socid.")";
+		}
 		if (! in_array($table_element, array('expensereport_det'))) $sql.= ' AND t.entity IN ('.getEntity('project',1).')';
 		if ($linkedtothirdparty) $sql.=" AND s.rowid = t.fk_soc";
 		if ($sqlfilter) $sql.= " AND ".$sqlfilter;
diff --git a/htdocs/projet/element.php b/htdocs/projet/element.php
index 2da7a6e5227..710807dcdec 100644
--- a/htdocs/projet/element.php
+++ b/htdocs/projet/element.php
@@ -640,9 +640,14 @@ foreach ($listofreferent as $key => $value)
 		$addform='';
 
 		$idtofilterthirdparty=0;
-		if (! in_array($tablename, array('facture_fourn', 'commande_fournisseur'))) $idtofilterthirdparty=$object->thirdparty->id;
+		$array_of_element_linkable_with_different_thirdparty = array('facture_fourn', 'commande_fournisseur');
+		if (! in_array($tablename, $array_of_element_linkable_with_different_thirdparty)) 
+		{
+		    $idtofilterthirdparty=$object->thirdparty->id;
+		    if (! empty($conf->global->PROJECT_OTHER_THIRDPARTY_ID_TO_ADD_ELEMENTS)) $idtofilterthirdparty.=','.$conf->global->PROJECT_OTHER_THIRDPARTY_ID_TO_ADD_ELEMENTS;
+		}
 
-       	if (empty($conf->global->PROJECT_LINK_ON_OVERWIEW_DISABLED) && $idtofilterthirdparty > 0)
+       	if (empty($conf->global->PROJECT_LINK_ON_OVERWIEW_DISABLED) && $idtofilterthirdparty)
        	{
 			$selectList=$formproject->select_element($tablename, $idtofilterthirdparty, 'minwidth300');
 			if (! $selectList || ($selectList<0))