Excel invoice and sales list generator

The project is for a business that provides language training to approximately 50 companies. Often (but not always) the training sessions will include people from different departments/subsidiaries of the same company, and each department needs to be billed separately according to how many of their people attend the sessions. The number of participants may change each month as people join or leave the company. Example Company A has 7 subsidiaries and 25 groups running once or twice a week. A typical scenario Group 1 has 10 participants, 3 from subsidiary W, 2 from sub X, 1 from sub Y and 4 from sub Z. The monthly cost for the group is €400, which needs to be split as €120 for subsidiary W, €80 for sub X, €40 for sub Y and €160 for sub Z. I have to produce a monthly invoice for each subsidiary that shows Course title course reference number No of hours programmed for the course The duration of the course The number of participants from the department An example of what we currently produce is shown in the pdf attached. It does not need to be in exactly the same format but it does need to contain all the same information. So in summary I need to be able to produce invoices (like the one described and attached), either from scatch or copied from a previous invoice, and then save them in a list to produce a monthly report. You will notice from the pdf attached that the language used is Spanish, however if the project can be written in English and edited, I can change headings into Spanish where necessary. As a final note, I know there are lots of free invoice generators that can do 95% of what I'm asking for which will just require me to set up a monthly template and edit it accordingly, however I have not found one that will automatically split the costs between each subsidiary.