Unable to add signer to existing package

We are trying to add signers to the package that was already sent through the API and keep getting the following exception: com.silanis.esl.sdk.internal.EslServerException: Could not add signer. Exception: HTTP POST on URI https://sandbox.e-signlive.ca/api/packages/bb5cd208-a565-4485-b66a-147e38ec4d61/roles resulted in response with status code: [403, Forbidden]. Optional details: {"entity":null,"messageKey":"error.forbidden.cannotEditDeletePkg","technical":"package: bb5cd208-a565-4485-b66a-147e38ec4d61 cannot be edited.","packageId":null,"code":403,"message":"Cannot edit or delete package.","name":"Access Denied"} at com.silanis.esl.sdk.service.PackageService.addSigner(PackageService.java:930) is there is a setup that allows us access to this functionality? The scenario we have to be able to achieve is the following: 1- First person signs 2- Once the first person completed, a supervisor will need to review the document and then send it to a second person to sign. Here is the code sample I am using: EslClient eslClient = new EslClient( API_KEY, API_URL ); PackageId packageId = new PackageId("bb5cd208-a565-4485-b66a-147e38ec4d61"); DocumentPackage docPackage = eslClient.getPackage(packageId); SignerBuilder signerBuilder = SignerBuilder.newSignerWithEmail("[email protected]"); signerBuilder.withFirstName("Sean"); signerBuilder.withLastName("G"); eslClient.getPackageService().addSigner(packageId, signerBuilder.build()); List documents = docPackage.getDocuments(); for(Document doc: documents){ SignatureBuilder signatureBuilder = SignatureBuilder.acceptanceFor("[email protected]"); eslClient.getApprovalService().addSignature(docPackage, doc.getId().getId(), signatureBuilder.build()); } eslClient.sendPackage(packageId); please advise. I could not find a clean sample code on the site, could you also direct me to a working sample?