diff --git a/packages/wyatt_form_bloc/lib/src/data/form_operations/form_difference.dart b/packages/wyatt_form_bloc/lib/src/data/form_operations/form_difference.dart
index 14a78d9c..ec77e957 100644
--- a/packages/wyatt_form_bloc/lib/src/data/form_operations/form_difference.dart
+++ b/packages/wyatt_form_bloc/lib/src/data/form_operations/form_difference.dart
@@ -30,12 +30,6 @@ class FormDifference extends FormOperation {
         FormInput<dynamic, FormInputValidator<dynamic, ValidationError>,
             dynamic>>[];
 
-    for (final i in b.inputs) {
-      if (!a.containsKey(i.key)) {
-        inputs.add(i);
-      }
-    }
-
     for (final i in a.inputs) {
       if (!b.containsKey(i.key)) {
         inputs.add(i);
diff --git a/packages/wyatt_form_bloc/lib/src/data/form_operations/form_intersection.dart b/packages/wyatt_form_bloc/lib/src/data/form_operations/form_intersection.dart
index 2c1d4cb6..332a7bd1 100644
--- a/packages/wyatt_form_bloc/lib/src/data/form_operations/form_intersection.dart
+++ b/packages/wyatt_form_bloc/lib/src/data/form_operations/form_intersection.dart
@@ -32,7 +32,11 @@ class FormIntersection extends FormOperation {
 
     for (final i in a.inputs) {
       if (b.containsKey(i.key)) {
-        inputs.add(i);
+        if (i.validator.pure) {
+          inputs.add(b.inputOf(i.key));
+        } else {
+          inputs.add(i);
+        }
       }
     }
 
diff --git a/packages/wyatt_form_bloc/lib/src/data/form_operations/form_union.dart b/packages/wyatt_form_bloc/lib/src/data/form_operations/form_union.dart
index a466750b..91725e13 100644
--- a/packages/wyatt_form_bloc/lib/src/data/form_operations/form_union.dart
+++ b/packages/wyatt_form_bloc/lib/src/data/form_operations/form_union.dart
@@ -37,6 +37,13 @@ class FormUnion extends FormOperation {
     for (final i in b.inputs) {
       if (!a.containsKey(i.key)) {
         inputs.add(i);
+      } else {
+        // if a input is pure, but not b, replace a one with b
+        if (a.isPureInput(i.key)) {
+          inputs
+            ..remove(a.inputOf(i.key))
+            ..add(i);
+        }
       }
     }