Yes, you can both sign a document and a mandate at the same time. To do that, you have to ask us first to set up your account for the redirection and not for the checkout which is the configuration by default. Indeed, the checkout does not go with a document signature. When your account is configured, you have to create a document template. This stage corresponds to a PDF file creation. This PDF contains text fields, some are compulsory and need names (SignatureDebtor for instance). Those fields wiil be filled in during the signature. Once this PDF created, you have to upload it in your backoffice. Now, you just need to make an API request #create-orders with two items. The first one is 'signMandate' type and the second one is 'templateBasedDocument' type. Within the document item, you need to fill in the document ID which is taken into account during the backoffice upload.