Ok.
I will probably do this but as I am not you 
… it will take some time.
Do you mind if I ask you if the (more basic) following is possible?
(I know that this is far from been perfect, I already found some bad points, like the waitress can delete her name, …)
Based on your idea, I put:
Cash Payment - {SETTING:CURRENTUSER} in the Description Template of the Customer Cash Document Type
Like this:
So now when my waitress Karina use the default Customer Cash button in the customer account to clear that account, the following transaction is created:
So now I have all the information I need in the transaction table
Customer account, Transaction Type, Waitress and amount.
Based on your post and on this post, the new version can now do:
[REPORT:1, 1]
{REPORT ACCOUNT TRANSACTION DETAILS:T.Target,T.Amount.Sum:(ATT=Payment Transaction)}
like in your post:
My questions for reporting are:
- What are the other filters (other than ATT) we can apply on REPORT ACCOUNT TRANSACTION DETAILS?
- Can we do sth like REPORT ACCOUNT TRANSACTION DETAILS:T.Source,T.Target,…:(T.Source=$1)
- And finally, sth like: REPORT ACCOUNT TRANSACTION DETAILS:T.Source,T.Name,…:(T.Name**%LIKE%**$1)
I don’t know if my questions make sence I am new with the reporting syntax.
Maybe a last one, I am in a place where internet is bad and I don’t imagine getting the GB of that Ms SQLServer tool, how to get the structure of the DB, Tables and so the names of the columns?
Marc