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Update Stylesheet of an existing Excel file using openXML

I am trying to copy an Excel workbook with 4 worksheets (tabs) where 1 worksheet is macro enabled with many formulas using the OpenXML SAX approach as I have lot of data for each sheet.
If I copy the file and and start writing into the worksheets, it starts writing from the 1st line and the headers are being deleted. So I tried copying just the macro-enabled sheet and add other sheets later and add styles to headers.
When I try doing it, the system give an error saying only one style sheet is allowed. Only one instance of the type is allowed for this parent.
How can I access the existing stylesheet and add more styling into it for other tabs?

VSTO / Excel make a file excel B be embedded in a file excel A, so that B inherit custom properties and validations from A

i have this problem to solve:
I have a "master" excel workbook, with custom validations and properties on some cells ( for example from Cell A1 to B2 you can only insert numbers etc...); furthermore i also made a custom add-in for excel, defined locally in the solution using Visual studio 2017 and VSTO (Visual studio tools for office).
What i'd like to do is: to embed in a cell of the "master" excel file, another excel file B, and i want that this file B inherit all the validations and properties from the "master" excel.
I need to embed and make it clickable so that the user's can make their own copy of the "master" excel on their machines.
Is it possible? Thanks in advance

Sounds like you just need to copy a worksheet in a workbook and remove any protection for changing the content. Use the Copy method which copies the sheet to another location in the current workbook or a new workbook. The following VBA code sample copies Sheet1, placing the copy after Sheet3.
Worksheets("Sheet1").Copy After:=Worksheets("Sheet3")
Use the Unprotect method to remove protection from a sheet or workbook. This method has no effect if the sheet or workbook isn't protected.

C# - How to save a single Excel WorkSheet in the current WorkBook?

I have seen some other existing questions about saving a single worksheet but the are regarding saving a worksheet in a new workbook (by copying it to the new workbook and then saving it. What I need is to save just one specific worksheet within the existing workbook, is to not possible?
Thank you!

No
If you check the list of Microsoft Office file specifications, none of them accommodate the storage of a single worksheet. So the answer to your question is no.
Yes
On the other hand, when you save as a non-Excel type such as CSV or TXT, Excel will only save the current sheet. So if you're OK with storing the worksheet in a non-native format, with possible data loss, then the answer is yes.

If you want to read worksheets programmatically then this might help you.
You can programmatically read each sheet in a workbook and save a particular sheet or a range of cells inside the sheet in the same workbook or as new sheet or as .txt,.csv and many other formats.. Use ByteScout and read about the documentation from here. There are many examples provided by them. Please let us know if you are facing any problem.

Data is reflected only when the Excel sheet is manually saved

I have an Excel report generation app using EPPlus. In one of sheets the formulas are getting dynamically updated, formulas referencing other sheets data. When I open the generated report I am able to see the formulas but the data is getting reflected only when I manually save the Excel sheet.
The reference sheet was also dynamically added, but when I changed it to static sheet the issue persisted.
Do I need to call some other function to update the formulas?

ok got it.
I need to call
package.Workbook.Calculate()

Excel Automation: read a csv file and update an Excel file

I have an automated test which produces a csv with two columns of data.
I have an excel file which I use to gather the results of all the runs in a worksheet.
I want to fully automate the process of updating the Excel file after each test run.
This is probably what I want to do:
1. Read the two columns from the CSV file
2. Paste the two columns in a worksheet in the excel file, in the first
empty column to the right of the existing block of columns.
3. Save the Excel file
EDIT:
Now i understand that i can do steps 1-3 using a macro.
All that is left for me to figure out is how to launch the macro.

You can read the csv and write to the Excel sheet with a single data provider, the OleDb provider. Here is an article on how to write to Excel, and here is one on how to read csv.

Once you write the macro, it should be in the macro list in Excel for that Excel document. You can bind the macro to a keystroke (like Alt-i, Alt-whatever) so that it runs when your press that key combination.
I've done this on a couple of similar projects where I need to import CSV files from other sources and put the data into an Excel sheet (or sheets)