diff --git a/src/Contracts/MultiSearchFederation.php b/src/Contracts/MultiSearchFederation.php
index 3f9db1ec..1f063ab5 100644
--- a/src/Contracts/MultiSearchFederation.php
+++ b/src/Contracts/MultiSearchFederation.php
@@ -16,6 +16,16 @@ class MultiSearchFederation
      */
     private ?int $offset = null;
 
+    /**
+     * @var array<non-empty-string, list<non-empty-string>>|null
+     */
+    private ?array $facetsByIndex = null;
+
+    /**
+     * @var array|null
+     */
+    private ?array $mergeFacets = null;
+
     /**
      * @param non-negative-int $limit
      *
@@ -40,10 +50,36 @@ public function setOffset(int $offset): self
         return $this;
     }
 
+    /**
+     * @param array<non-empty-string, list<non-empty-string>> $facetsByIndex
+     *
+     * @return $this
+     */
+    public function setFacetsByIndex(array $facetsByIndex): self
+    {
+        $this->facetsByIndex = $facetsByIndex;
+
+        return $this;
+    }
+
+    /**
+     * @param array $mergeFacets
+     *
+     * @return $this
+     */
+    public function setMergeFacets(array $mergeFacets): self
+    {
+        $this->mergeFacets = $mergeFacets;
+
+        return $this;
+    }
+
     /**
      * @return array{
      *     limit?: non-negative-int,
-     *     offset?: non-negative-int
+     *     offset?: non-negative-int,
+     *     facetsByIndex?: array<non-empty-string, list<non-empty-string>>,
+     *     mergeFacets?: array,
      * }
      */
     public function toArray(): array
@@ -51,6 +87,8 @@ public function toArray(): array
         return array_filter([
             'limit' => $this->limit,
             'offset' => $this->offset,
+            'facetsByIndex' => $this->facetsByIndex,
+            'mergeFacets' => $this->mergeFacets,
         ], static function ($item) { return null !== $item; });
     }
 }
diff --git a/tests/Contracts/MultiSearchFederationTest.php b/tests/Contracts/MultiSearchFederationTest.php
index 191b3692..ec002b21 100644
--- a/tests/Contracts/MultiSearchFederationTest.php
+++ b/tests/Contracts/MultiSearchFederationTest.php
@@ -29,4 +29,18 @@ public function testSetOffset(): void
 
         self::assertSame(['offset' => 5], $data->toArray());
     }
+
+    public function testSetFacetsByIndex(): void
+    {
+        $data = (new MultiSearchFederation())->setFacetsByIndex(['books' => ['author', 'genre']]);
+
+        self::assertSame(['facetsByIndex' => ['books' => ['author', 'genre']]], $data->toArray());
+    }
+
+    public function testSetMergeFacets(): void
+    {
+        $data = (new MultiSearchFederation())->setMergeFacets(['maxValuesPerFacet' => 10]);
+
+        self::assertSame(['mergeFacets' => ['maxValuesPerFacet' => 10]], $data->toArray());
+    }
 }
diff --git a/tests/Endpoints/MultiSearchTest.php b/tests/Endpoints/MultiSearchTest.php
index 0352cae0..c6b7c909 100644
--- a/tests/Endpoints/MultiSearchTest.php
+++ b/tests/Endpoints/MultiSearchTest.php
@@ -89,7 +89,7 @@ public function testFederation(): void
                 // By setting the weight to 0.9 this query should appear second
                 ->setFederationOptions((new FederationOptions())->setWeight(0.9)),
         ],
-            (new MultiSearchFederation())->setLimit(2)
+            (new MultiSearchFederation())->setLimit(2)->setFacetsByIndex(['books' => ['genre']])->setMergeFacets(['maxValuesPerFacet' => 10])
         );
 
         self::assertArrayHasKey('hits', $response);
@@ -97,6 +97,7 @@ public function testFederation(): void
         self::assertArrayHasKey('limit', $response);
         self::assertArrayHasKey('offset', $response);
         self::assertArrayHasKey('estimatedTotalHits', $response);
+        self::assertArrayHasKey('facetDistribution', $response);
         self::assertCount(2, $response['hits']);
         self::assertSame(2, $response['limit']);
         self::assertSame(0, $response['offset']);