diff --git a/client/app/scripts/actions/app-actions.js b/client/app/scripts/actions/app-actions.js
index badb484d1..ae25c8770 100644
--- a/client/app/scripts/actions/app-actions.js
+++ b/client/app/scripts/actions/app-actions.js
@@ -174,13 +174,14 @@ export function blurSearch() {
   return { type: ActionTypes.BLUR_SEARCH };
 }
 
-export function changeTopologyOption(option, value, topologyId) {
+export function changeTopologyOption(option, value, topologyId, addOrRemove) {
   return (dispatch, getState) => {
     dispatch({
       type: ActionTypes.CHANGE_TOPOLOGY_OPTION,
       topologyId,
       option,
-      value
+      value,
+      addOrRemove
     });
     updateRoute(getState);
     // update all request workers with new options
diff --git a/client/app/scripts/components/topology-options.js b/client/app/scripts/components/topology-options.js
index f6cd8724e..c4276c28e 100644
--- a/client/app/scripts/components/topology-options.js
+++ b/client/app/scripts/components/topology-options.js
@@ -18,13 +18,9 @@ class TopologyOptions extends React.Component {
     const selectedOption = options.find(o => o.get('id') === optionId);
 
     if (selectedOption.get('selectType') === 'union') {
-      if (activeOptions.get(selectedOption.get('id')).includes(value)) {
-        // Option already exists; user is de-selecting
-        console.log('TODO! removeOption action');
-      } else {
-        // Option does not exist; user is enabling.
-        console.log('TODO! addOption action');
-      }
+      const isSelectedAlready = activeOptions.get(selectedOption.get('id')).includes(value);
+      const addOrRemove = isSelectedAlready ? 'remove' : 'add';
+      this.props.changeTopologyOption(optionId, value, topologyId, addOrRemove);
     } else {
       this.props.changeTopologyOption(optionId, value, topologyId);
     }
diff --git a/client/app/scripts/reducers/__tests__/root-test.js b/client/app/scripts/reducers/__tests__/root-test.js
index 7d5e9e002..ec7993be7 100644
--- a/client/app/scripts/reducers/__tests__/root-test.js
+++ b/client/app/scripts/reducers/__tests__/root-test.js
@@ -368,22 +368,32 @@ describe('RootReducer', () => {
 
   it('adds/removes a topology option', () => {
     const addAction = {
-      type: ActionTypes.ADD_TOPOLOGY_OPTION,
+      type: ActionTypes.CHANGE_TOPOLOGY_OPTION,
       topologyId: 'services',
       option: 'namespace',
-      value: 'scope'
+      value: 'scope',
+      addOrRemove: 'add'
     };
     const removeAction = {
-      type: ActionTypes.REMOVE_TOPOLOGY_OPTION,
+      type: ActionTypes.CHANGE_TOPOLOGY_OPTION,
       topologyId: 'services',
       option: 'namespace',
-      value: 'scope'
+      value: 'scope',
+      addOrRemove: 'remove'
     };
     let nextState = initialState;
     nextState = reducer(nextState, { type: ActionTypes.RECEIVE_TOPOLOGIES, topologies});
     nextState = reducer(nextState, { type: ActionTypes.CLICK_TOPOLOGY, topologyId: 'services' });
-
     nextState = reducer(nextState, addAction);
+    expect(activeTopologyOptionsSelector(nextState).toJS()).toEqual({
+      namespace: ['default', 'scope'],
+      pseudo: ['hide']
+    });
+    nextState = reducer(nextState, removeAction);
+    expect(activeTopologyOptionsSelector(nextState).toJS()).toEqual({
+      namespace: ['default'],
+      pseudo: ['hide']
+    });
   });
 
   it('sets topology options from route', () => {
diff --git a/client/app/scripts/reducers/root.js b/client/app/scripts/reducers/root.js
index 536d5a3f2..3e673e837 100644
--- a/client/app/scripts/reducers/root.js
+++ b/client/app/scripts/reducers/root.js
@@ -1,6 +1,6 @@
 /* eslint-disable import/no-webpack-loader-syntax, import/no-unresolved */
 import debug from 'debug';
-import { size, each, includes } from 'lodash';
+import { size, each, includes, isEqual } from 'lodash';
 import { fromJS, is as isDeepEqual, List as makeList, Map as makeMap,
   OrderedMap as makeOrderedMap, Set as makeSet } from 'immutable';
 
@@ -194,15 +194,21 @@ export function rootReducer(state = initialState, action) {
       // set option on parent topology
       const topology = findTopologyById(state.get('topologies'), action.topologyId);
       if (topology) {
+        let values = [action.value];
         const topologyId = topology.get('parentId') || topology.get('id');
+        const optionKey = ['topologyOptions', topologyId, action.option];
         const currentOption = state.getIn(['topologyOptions', topologyId, action.option]);
-        if (currentOption !== action.value) {
+
+        if (!isEqual(currentOption, action.value)) {
           state = clearNodes(state);
         }
-        state = state.setIn(
-          ['topologyOptions', topologyId, action.option],
-          [action.value]
-        );
+
+        if (action.addOrRemove === 'add') {
+          values = state.getIn(optionKey).concat(values);
+        } else if (action.addOrRemove === 'remove') {
+          values = state.getIn(optionKey).filter(o => !values.includes(o));
+        }
+        state = state.setIn(optionKey, values);
       }
       return state;
     }