diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5255f87e..7f69624e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -105,6 +105,8 @@ Please also have a look at our
 
 ### Fixed
 
+- Insert `Rule` before sibling even with different property name
+  (in `RuleSet::addRule()`) (#1270)
 - Ensure `RuleSet::addRule()` sets non-negative column number when sibling
   provided (#1268)
 - Set line number when `RuleSet::addRule()` called with only column number set
diff --git a/src/RuleSet/RuleSet.php b/src/RuleSet/RuleSet.php
index b24eefab..8e0e8ae5 100644
--- a/src/RuleSet/RuleSet.php
+++ b/src/RuleSet/RuleSet.php
@@ -104,9 +104,25 @@ public function addRule(Rule $ruleToAdd, ?Rule $sibling = null): void
         $position = \count($this->rules[$propertyName]);
 
         if ($sibling !== null) {
+            $siblingIsInSet = false;
             $siblingPosition = \array_search($sibling, $this->rules[$propertyName], true);
             if ($siblingPosition !== false) {
+                $siblingIsInSet = true;
                 $position = $siblingPosition;
+            } else {
+                $siblingIsInSet = $this->hasRule($sibling);
+                if ($siblingIsInSet) {
+                    // Maintain ordering within `$this->rules[$propertyName]`
+                    // by inserting before first `Rule` with a same-or-later position than the sibling.
+                    foreach ($this->rules[$propertyName] as $index => $rule) {
+                        if (self::comparePositionable($rule, $sibling) >= 0) {
+                            $position = $index;
+                            break;
+                        }
+                    }
+                }
+            }
+            if ($siblingIsInSet) {
                 // Increment column number of all existing rules on same line, starting at sibling
                 $siblingLineNumber = $sibling->getLineNumber();
                 $siblingColumnNumber = $sibling->getColumnNumber();
@@ -123,6 +139,7 @@ public function addRule(Rule $ruleToAdd, ?Rule $sibling = null): void
                 $ruleToAdd->setPosition($siblingLineNumber, $siblingColumnNumber);
             }
         }
+
         if ($ruleToAdd->getLineNumber() === null) {
             //this node is added manually, give it the next best line
             $columnNumber = $ruleToAdd->getColumnNumber() ?? 0;
@@ -305,4 +322,15 @@ private static function comparePositionable(Positionable $first, Positionable $s
         }
         return $first->getLineNo() - $second->getLineNo();
     }
+
+    private function hasRule(Rule $rule): bool
+    {
+        foreach ($this->rules as $rulesForAProperty) {
+            if (\in_array($rule, $rulesForAProperty, true)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }
diff --git a/tests/Unit/RuleSet/RuleSetTest.php b/tests/Unit/RuleSet/RuleSetTest.php
index 5b2bfa7a..03cacd85 100644
--- a/tests/Unit/RuleSet/RuleSetTest.php
+++ b/tests/Unit/RuleSet/RuleSetTest.php
@@ -221,8 +221,6 @@ public function addRuleWithSiblingInsertsRuleBeforeSibling(
         int $siblingIndex,
         string $propertyNameToAdd
     ): void {
-        self::markTestSkipped('tofix: if property names don\'t match, sibling is ignored');
-
         $ruleToAdd = new Rule($propertyNameToAdd);
         $this->setRulesFromPropertyNames($initialPropertyNames);
         $sibling = $this->subject->getRules()[$siblingIndex];