diff --git a/data/src/main/java/one/nem/kidshift/data/ChildData.java b/data/src/main/java/one/nem/kidshift/data/ChildData.java
new file mode 100644
index 0000000..f6e8863
--- /dev/null
+++ b/data/src/main/java/one/nem/kidshift/data/ChildData.java
@@ -0,0 +1,4 @@
+package one.nem.kidshift.data;
+
+public interface ChildData {
+}
diff --git a/data/src/main/java/one/nem/kidshift/data/ParentData.java b/data/src/main/java/one/nem/kidshift/data/ParentData.java
new file mode 100644
index 0000000..f44a4ec
--- /dev/null
+++ b/data/src/main/java/one/nem/kidshift/data/ParentData.java
@@ -0,0 +1,4 @@
+package one.nem.kidshift.data;
+
+public interface ParentData {
+}