Batch Data Import to Google Sheets

Hi,

Thank you very much for taking out time and trying to help me out. Here is what I am stuck with :

1. I have a list of around 4000 companies
2. Each of those companies have three financial statements (two of them enclosed for reference)
3. Therefore I have around 12000 sheets to work with
4. Each of these sheets update every 3 months, but only the data changes. Headings and Column 1 does not change. Nor does the number of fields.
5. I need to upload these to Google Sheets every 3 months.
6. Another master Google Sheet references data from these 12000 sheets.
7. Therefore, the cell data can change, but not the references.

Here is what I have figured out :


1. Manually upload each of these 12000 sheets to Google sheets using the Import option.
2. Every 3 months, repeat the action using the "replace sheet"option. This leaves the sheet URL unchanged, which is required for referencing data on another Master sheet using the IMPORTRANGE function.
This is a tedious process.

Is there any way I could

1. merge 3 sheets for the same company in a batch operation so that I need to upload only 4000 times ? OR
2. Auto import the data if I replace the existing files in my hard drive with the newly downloaded files ? The filenames will be exactly the same.

The whole idea is to automate this tedious process to the largest extent possible. Request your suggestions and advice please.

P.S. I am a basic excel user and have no coding knowledge.

best,
Somnath.