Have you explored having a separate table for those tabs that you sometimes need extra details for? You would have a report link field there that showed all related things plus a button for "Add Expense" or whatever it will be named. A user could then add related records there for each expense associated with the order and the report link would show all related expenses. You would probably then need to make a summary field to total these for you.
Then all a user would need is the ability to add and they could add new expense records in any amount for that order. You could then do this for any tab that needs the same with different tables. For the one picture with Description, Rental, etc text boxes this should work great.