Collating multiple sales report tables into one master sheet

Hi everybody,

I'm fairly confident this is not the most efficient method of retrieving the information I require but unfortunately our data systems at my work have been vastly underutilised for years and so until such a time as I've managed to correct said systems, I have been collating our sales data onto master spreadsheets. Dependant on ordering frequency, I gather sales figures be they daily, monthly or otherwise and collate them all onto one day by day/month by month worksheet allowing me to perform the necessary analysis. Albeit slow, this method works for smaller ranges of products.

THE PROBLEM: Our till system generates the data I need in reports called "article league tables". More or less, these are reports showing various sales figures for active products over a specified period of time. If something has sold within the determined time period, it will appear on the "article league table". This is where the problem begins. For smaller ranges or ranges where we consistently sell every item in said range, collating the necessary data is simple. I simply alphabetise by article name and copy paste the figures next to their respective articles, adjusting and adding missing articles where necessary. The larger reports, however, do not always encompass the entire range I am looking to analyse and as such, the alphabetising method cannot be used as efficiently as there is no certainty the same products have sold on each report and thus the article listings between reports may be different.

TL/DR: I need to be able to list numerical sales data, day by day, from multiple spreadsheets alongside an article listing that changes dependant on the sales in the report. Examples attached.

Thanks in advance for any help you can give!