Right now, it seems that the Quote/Invoice/Revenue modules are standalone. Most typical workflow would be the creation of a Quote to a client, receive approval or change request to adjust the Quote (then reissue with same quote number but with a change indicator such as QUOTE-01a, QUOTE-01b), client accept Quote either via email/phone/digital signing which then should convert the Quote into an Invoice.
The Quote number will be referenced in the automatically generated Invoice, while the line items that were quoted/adjusted will automatically fill up the Invoice and be issued to the client via email or PDF.
As payment may be via Bank Transfer (most probable) or Stripe or Cash, there should be just a "Paid" button within the Invoice which when clicked, will ask the user how was the payment received. User will select the means of payment used and the system should automatically convert the Invoice into Revenue.
This would be really helpful in my view. What do you think?