Here are the steps :
1. First you can goto your Sales Order tab AND then group by the Partner , hint : go to the search box , select Partner from the drop down ...
2. then from the selected partner , click and open the group and select which Sales Order you wish to monitor the invoices , i.e. for us , we use Sales Order as the way to manage our Projects , we quote customer in the Sales Order but we will only issues invoices to our customer based on the progressive terms and conditions ... so some times is hard to track how many invoices if not with this features , we have to check manually every time.
3. after the Sales Order form is opened , then go to the Tab History , (this is a custom modules , name : sale_invoice_manual_link , you should be able to find it ,just key in the MIGHTY GOOGLE SEARCH BOX !) , then you will be able to find the original invoices which has been issued /created previously.
But of course if there is any Credit Note or the Invoices that has issued by manually not from the Create invoice function of Sales Order , then you should not be able to find it here, so the module able to help you to add the invoices in that i just mentioned into the sales order.
4. Here is should you the explanation of the History tab ...
5. So now if you need to add what has been issued / invoice ad-hoc / manually created but which is related to the Sales Order of this partner , then you need to
click the EDIT button of the Sales Order and here ... after enter in EDIT mode, you can find the ADD button appear magically at the HISTORY tab !
so this is how we can use a very simple module to manage the link of Sales Order and invoices and to do a simple tracking . But of course there are many ways to improve this , but no cost who wish to do it for FREE ? i am using it myself without customization , just what it provide , take and use and compromise it like any of you SME will do la !
until we can make some money , i mean survive and profitable ... or else , no one is paying the salary , wo ... wo ... (crying ...)
things that we can improved this Odoo Module :
1. to make a total of Sales order amount that can take into consideration of
the invoices and credit notes
2. to be able to show CORRECT balance for each invoice in this History
tab , currently it wasn't display a correct balance.
3. Can print out so that we can file it or send it to Customer for the history
when our client request of it.
So till them SME Malaysia /Singapore , will see you around ,please come back , we are planning to launching something interested soon !