diff --git a/constellations/__init__.py b/constellations/__init__.py
index 0d4e793..492046a 100644
--- a/constellations/__init__.py
+++ b/constellations/__init__.py
@@ -1,3 +1,3 @@
 _program = "constellations"
-__version__ = "v0.0.18"
+__version__ = "v0.0.19"
 
diff --git a/constellations/definitions/cAY.4.json b/constellations/definitions/cAY.4.json
index 91efd32..8282827 100644
--- a/constellations/definitions/cAY.4.json
+++ b/constellations/definitions/cAY.4.json
@@ -11,6 +11,9 @@
 	"mrca_lineage": "AY.4",
         "lineage_name": "AY.4",
         "parent_lineage": "B.1.617.2",
+        "incompatible_lineage_calls": [
+            "AY.4.2"
+        ],
 	"representative_genome": ""
     },
     "tags": [
diff --git a/constellations/definitions/cB.1.617.2+K417N.json b/constellations/definitions/cB.1.617.2+K417N.json
index 44f2ef3..70bdaa2 100644
--- a/constellations/definitions/cB.1.617.2+K417N.json
+++ b/constellations/definitions/cB.1.617.2+K417N.json
@@ -11,7 +11,11 @@
             "AY.2",
             "B.1.617.2"
         ],
-	    "mrca_lineage": "B.1.617.2",
+        "incompatible_lineage_calls": [
+            "AY.4",
+            "AY.4.2"
+        ],
+	"mrca_lineage": "B.1.617.2",
         "representative_genome": ""
     },
     "tags": [
diff --git a/constellations/definitions/cB.1.617.2.json b/constellations/definitions/cB.1.617.2.json
index 8ab12a4..11e0514 100644
--- a/constellations/definitions/cB.1.617.2.json
+++ b/constellations/definitions/cB.1.617.2.json
@@ -14,8 +14,8 @@
 	    "mrca_lineage": "B.1.617.2",
         "lineage_name": "B.1.617.2",
         "incompatible_lineage_calls": [
-            "AY.1",
-            "AY.2"
+            "AY.4",
+            "AY.4.2"
         ],
         "PHE_label": "VOC-21APR-02",
         "WHO_label": "Delta",