diff --git a/src/app/api/plan/trigger/route.ts b/src/app/api/plan/trigger/route.ts
index baa49a66..9746b392 100644
--- a/src/app/api/plan/trigger/route.ts
+++ b/src/app/api/plan/trigger/route.ts
@@ -17,6 +17,8 @@ const PresignedUrlBodySchema = z.object({
   inclusions: z.array(MeasureKeyEnum).optional(),
   exclusions: z.array(MeasureKeyEnum).optional(),
   already_installed_file_path: z.string().optional(),
+  // optional scenario_id to link the plan to an existing scenario
+  scenario_id: z.string().optional().nullable(),
 });
 
 export async function POST(request: NextRequest) {
diff --git a/src/app/portfolio/[slug]/components/RemoteAssessmentDropdowns.tsx b/src/app/portfolio/[slug]/components/RemoteAssessmentDropdowns.tsx
index e056dd3f..1da5392f 100644
--- a/src/app/portfolio/[slug]/components/RemoteAssessmentDropdowns.tsx
+++ b/src/app/portfolio/[slug]/components/RemoteAssessmentDropdowns.tsx
@@ -72,6 +72,7 @@ export function SelectScenarioDropdown({
             <Menu.Item key={opt.value}>
               {({ active }) => (
                 <button
+                  type="button"
                   onClick={() => onSelect(opt)}
                   className={
                     `group w-full text-left px-4 py-3 text-sm transition-colors flex flex-col space-y-1 ` +
diff --git a/src/app/portfolio/[slug]/components/RemoteAssessmentModal.tsx b/src/app/portfolio/[slug]/components/RemoteAssessmentModal.tsx
index 81ac22c1..c411ac8d 100644
--- a/src/app/portfolio/[slug]/components/RemoteAssessmentModal.tsx
+++ b/src/app/portfolio/[slug]/components/RemoteAssessmentModal.tsx
@@ -158,6 +158,7 @@ interface EngineTriggerBody {
   budget: null;
   event_type: string;
   inclusions: (typeof measuresList)[number][];
+  scenario_id?: string | null;
 }
 
 const formSchema = z.object({
@@ -169,9 +170,9 @@ const formSchema = z.object({
   postcode: z.string().min(1),
   uprn: z.number().min(1),
   valuation: z.number().min(1),
-  propertyType: z.string().optional().nullable(),
-  builtForm: z.string().optional().nullable(),
-  measures: z.array(MeasureKeyEnum),
+  propertyType: z.string().nullable(),
+  builtForm: z.string().nullable(),
+  measures: z.array(MeasureKeyEnum).min(1, "Select at least one measure."),
 });
 
 type FormValues = z.infer<typeof formSchema>;
@@ -276,6 +277,7 @@ function useCreateRemoteAssessment({
   propertyType,
   builtForm,
   measures,
+  scenarioId,
 }: {
   portfolioId: string;
   uprn: number | null;
@@ -285,6 +287,7 @@ function useCreateRemoteAssessment({
   measures: (typeof measuresList)[number][];
   propertyType?: string | null;
   builtForm?: string | null;
+  scenarioId?: string | null;
 }) {
   // 1) We want to upload the asset data. To do this, we format the asset data, generate a presigned URL, and upload the data to S3.
   // 2) We then want to upload valuation data. To do this, we format the valuation data, generate a presigned URL, and upload the data to S3.
@@ -367,6 +370,7 @@ function useCreateRemoteAssessment({
   async function triggerEngine(data: FormValues) {
     try {
       const triggerBody: EngineTriggerBody = {
+        scenario_id: scenarioId || null,
         portfolio_id: portfolioId,
         housing_type: data.housingType,
         goal: data.goal,
@@ -454,7 +458,7 @@ export default function RemoteAssessmentModal({
     () => [
       ...scenarios.map((s) => ({
         label: s.name || "",
-        value: s.name || "",
+        value: String(s.id) || "",
         disabled: false,
       })),
     ],
@@ -465,6 +469,7 @@ export default function RemoteAssessmentModal({
 
   const form = useForm({
     resolver: zodResolver(formSchema),
+    mode: "onChange",
     defaultValues: {
       scenario: "",
       housingType: "",
@@ -474,12 +479,15 @@ export default function RemoteAssessmentModal({
       postcode: "",
       uprn: 0,
       valuation: 0,
-      propertyType: null,
-      builtForm: null,
+      propertyType: null as string | null,
+      builtForm: null as string | null,
       measures: measuresList,
     },
   });
-  const { reset, setValue } = form;
+  const { reset, setValue, formState } = form;
+  const { isValid, isSubmitting } = formState;
+
+  const measures = form.watch("measures");
 
   const {
     handleSubmit: triggerAssessment,
@@ -493,7 +501,8 @@ export default function RemoteAssessmentModal({
     valuation: form.watch("valuation"),
     propertyType: form.watch("propertyType"),
     builtForm: form.watch("builtForm"),
-    measures: form.watch("measures"),
+    measures: measures,
+    scenarioId: selectedScenario,
   });
 
   const onSelectScenario = (opt: Option) => {
@@ -507,7 +516,8 @@ export default function RemoteAssessmentModal({
         goalValue: "",
       });
     } else {
-      const picked = scenarios.find((s) => s.name === opt.value);
+      const picked = scenarios.find((s) => String(s.id) === opt.value);
+
       if (!picked) return;
       setValue("scenario", picked.name || "");
       setValue("housingType", picked.housingType);
@@ -840,7 +850,7 @@ export default function RemoteAssessmentModal({
                       <span>Measures</span>
                       <span>{showMeasures ? "−" : "+"}</span>
                     </button>
-                    {showMeasures && <MeasuresCheckboxes />}
+                    {showMeasures && <MeasuresCheckboxes form={form} />}
                   </div>
 
                   <div className="flex justify-end gap-4">
@@ -851,8 +861,15 @@ export default function RemoteAssessmentModal({
                     >
                       Cancel
                     </Button>
-                    <Button type="submit" disabled={presignedUrlIsLoading}>
-                      {presignedUrlIsLoading ? "Submitting…" : "Submit"}
+                    <Button
+                      type="submit"
+                      disabled={
+                        !isValid || presignedUrlIsLoading || isSubmitting
+                      }
+                    >
+                      {isSubmitting || presignedUrlIsLoading
+                        ? "Submitting…"
+                        : "Submit"}
                     </Button>
                   </div>
 
@@ -872,40 +889,69 @@ function setIsOpen(arg0: boolean) {
   throw new Error("Function not implemented.");
 }
 
-function MeasuresCheckboxes() {
-  const { control } = useFormContext();
+function MeasuresCheckboxes({
+  form,
+}: {
+  form: ReturnType<typeof useForm<FormValues>>;
+}) {
+  const { control } = form;
+  const allMeasures = measuresList;
   return (
-    <div className="grid grid-cols-2 gap-4 mt-4">
-      {measuresList.map((measure) => (
-        <FormField
-          key={measure}
-          control={control}
-          name="measures"
-          render={({ field }) => (
-            <FormItem className="flex items-center space-x-2">
-              <input
-                type="checkbox"
-                value={measure}
-                checked={field.value?.includes(measure) ?? true}
-                onChange={(e) => {
-                  const checked = e.target.checked;
-                  const current = new Set(field.value ?? []);
-                  if (checked) {
-                    current.add(measure);
-                  } else {
-                    current.delete(measure);
-                  }
-                  field.onChange(Array.from(current));
-                }}
-                className="h-4 w-4"
-              />
-              <FormLabel className="text-sm">
-                {measuresDisplayLabels[measure]}
-              </FormLabel>
-            </FormItem>
-          )}
-        />
-      ))}
+    <div className="flex flex-col gap-4 mt-4 ">
+      <div className="flex justify-start gap-4">
+        <button
+          type="button"
+          onClick={() =>
+            form.setValue("measures", allMeasures, { shouldValidate: true })
+          }
+          className="text-sm text-brandbrown underline"
+        >
+          Select All
+        </button>
+        <button
+          type="button"
+          onClick={() =>
+            form.setValue("measures", [], { shouldValidate: true })
+          }
+          className="text-sm text-brandbrown underline"
+        >
+          Untick All
+        </button>
+      </div>
+
+      {/* Measures grid */}
+      <div className="grid grid-cols-2 gap-4">
+        {measuresList.map((measure) => (
+          <FormField
+            key={measure}
+            control={control}
+            name="measures"
+            render={({ field }) => (
+              <FormItem className="flex items-center space-x-2">
+                <input
+                  type="checkbox"
+                  value={measure}
+                  checked={field.value?.includes(measure) ?? true}
+                  onChange={(e) => {
+                    const checked = e.target.checked;
+                    const current = new Set(field.value ?? []);
+                    if (checked) {
+                      current.add(measure);
+                    } else {
+                      current.delete(measure);
+                    }
+                    field.onChange(Array.from(current));
+                  }}
+                  className="h-4 w-4"
+                />
+                <FormLabel className="text-sm">
+                  {measuresDisplayLabels[measure]}
+                </FormLabel>
+              </FormItem>
+            )}
+          />
+        ))}
+      </div>
     </div>
   );
 }