Can you please provide more details on your requirement?
Kindly see the following thread which could have the answer for your question
If this answer solved your question or if you found it helpful please mark it accordingly to help others who have the same question.
Are you using two survey forms? One survey to have users submit a sketch, and then another for users to review it via the Inbox?
There are currently some limitations with pulling down attachments (such as images) into an Inbox. While we can editing existing surveys, and add more attachments, we cannot edit or work with existing attachments.
If you can provide more information on your workflow, ideal outcome and current forms/setup it will greatly assist Rawan, myself and others in providing help.