diff --git a/src/request-management/request-management.service.ts b/src/request-management/request-management.service.ts
index 95c04c1..4366c3e 100644
--- a/src/request-management/request-management.service.ts
+++ b/src/request-management/request-management.service.ts
@@ -278,6 +278,32 @@ export class RequestManagementService {
       return;
     }
 
+    // IN_PERSON THIRD_PARTY (expert/registrar-initiated): after first-party description
+    // the expert collects the first party's signature before moving to the second party.
+    // Skip FIRST_INVITE_SECOND and hold at WAITING_FOR_SIGNATURES so the sign endpoint
+    // can be called for the first party. The workflow advances to FIRST_INVITE_SECOND
+    // only after expertUploadPartySignatureV2/V3 records the first-party confirmation.
+    if (
+      req.type === BlameRequestType.THIRD_PARTY &&
+      req.creationMethod === CreationMethod.IN_PERSON &&
+      (req.expertInitiated || req.registrarInitiated) &&
+      submittedStepKey === WorkflowStep.FIRST_DESCRIPTION
+    ) {
+      const completed = Array.isArray(req.workflow.completedSteps)
+        ? req.workflow.completedSteps
+        : [];
+      if (!completed.includes(submittedStepKey))
+        completed.push(submittedStepKey);
+      req.workflow.completedSteps = completed;
+      req.workflow.currentStep = WorkflowStep.WAITING_FOR_SIGNATURES;
+      req.workflow.nextStep = undefined;
+      req.status = CaseStatus.WAITING_FOR_SIGNATURES;
+      this.logger.debug(
+        "[WORKFLOW] IN_PERSON THIRD_PARTY: advanced to WAITING_FOR_SIGNATURES after FIRST_DESCRIPTION (first-party sign before second-party invite)",
+      );
+      return;
+    }
+
     // IN_PERSON THIRD_PARTY: guilt is decided on-site by the expert — there is
     // no waiting-for-field-expert phase. Replace WAITING_FOR_GUILT_DECISION
     // with WAITING_FOR_SIGNATURES wherever it would surface as current/next step.
@@ -6728,6 +6754,23 @@ export class RequestManagementService {
           },
         });
       }
+    } else if (
+      // THIRD_PARTY IN_PERSON: first party just signed — advance workflow to
+      // FIRST_INVITE_SECOND so the frontend knows to proceed to the second-party
+      // registration step. Status stays WAITING_FOR_SIGNATURES.
+      req.type === BlameRequestType.THIRD_PARTY &&
+      req.creationMethod === CreationMethod.IN_PERSON &&
+      (req.expertInitiated || req.registrarInitiated) &&
+      partyRole === PartyRole.FIRST
+    ) {
+      await this.blameRequestDbService.findByIdAndUpdate(requestId, {
+        $set: {
+          "workflow.currentStep": WorkflowStep.FIRST_INVITE_SECOND as any,
+          "workflow.nextStep": WorkflowStep.SECOND_INITIAL_FORM as any,
+        },
+      });
+      message =
+        "First party signature recorded. Proceed to register the second party.";
     }
     return {
       requestId: String(req._id),