You can prefill the signers of your documents with data coming from Salesforce. For that, you can use the SignRequest SetUp page of our Salesforce package.
If it's the first time you are creating a setup for SignRequest for Salesforce to either a Standard (Contacts, Lead or Opportunities, for example) or Custom Object, and wishes to prefill your documents with signers existing in those objects, you should open 'SignRequest SetUp' in Salesforce Lightning. See image below:
In the SignRequest SetUp page, you can find Advanced Settings, click on it.
You will find a box where you can prefill your document signers with data coming from your Salesforce Standard Objects, such as Contact, used in the example below.
On the 'Email' field you can assign strings existent in Salesforce's objects to the e-mail addresses of your signers. In the next field, you can choose a Signer Level, which can take 'signature', 'cc', 'notify' or 'approve'. The next field is Order, which takes a number starting from 0. Important, signing orders 0 are always associated to the document's sender. This field defines the order in which the document should be signed, starting by the document's sender and followed by the signers starting with an order 1.
Make sure you prepare your documents with placeholders specific for the signing order above. So, if you wish to create a checkbox [[c|1| id: checkbox_value]] for one of your signers above, this checkbox should contain an index 1, which is the same as the signing order.
Note: when using a lookup between different objects, the format of your code will change. For example, when using a lookup from Contact to Opportunity. The format will be:
For more information, check: https://help.salesforce.com/articleView?id=overview_of_custom_object_relationships.htm&type=5