The integration between CRM and Books is great, but it is incomplete in many areas. One of them is if an estimate/invoice/sales order is rejected, the users in CRM cannot resubmit it for approval. Let's face it, sales people will mostly be in CRM and would not be in Books, but they are the ones who would ask for approval. Not being able to resubmit for approval in CRM is a great inconvenience. Let's think of the general public for a moment, and not jump into custom function workaround at a whim because not everyone has the capability nor the temperament for it. Make it a standard function. Really hope Zoho can implement this.