Excel formula keep fixed

Hello I attached a sample Spreadsheet. It has 2 worksheets (Sheet1 and Sheet2).
In Sheet2 It has 3 columns and 3 rows of numbers. On Sheet1 there are formulas that reference the numbers in Sheet2 and add them up. However, I want to know if there is a way that formulas in Sheet1 will not change, even if I delete a column in Sheet2. I need to delete columns in Sheet2 and then I add in another Column later. However, once I delete a column in Sheet2, even if I add a column back in later, the formulas in Sheet1 are showing the Sheet2!#REF error.
The actual sheet I am working on is much more involved then the sample I provided, so when I need to fix the #REF error it is very time consuming process. Thanks for any suggestions on this.

sorry I forgot to put the version, it is Excel 2019.

I read the forum rules. however, I am not sure what I need to update in my profile (please let me know what is Required info I need to provide in my profile). Thank you. As for hiding the columns, it would take me too long to explain why I that wouldn't work. If there isn't a way to do this, then I will just have to update all the formulas whenever i need to update the sheet, its just very time consuming that is why I thought perhaps there might be another way to do this. Thanks.

Thanks. I updated the Excel version in Profile. As for Microsoft VBA, thanks for mentioning it, but I don't want to do a Macro for this worksheet. If that is the only option, I will just live with it as is and then update the formulas as needed.

Sorry for the slow reply, I am in a different time zone and had to rest. Thanks very much! That is quite an impressive formula, I never worked with =LET before. I am using Excel 2019 to work with the Excel spreadsheet on a different computer. The Excel Version I have saved in my profile is the computer I am using currently on home computer. (I had just copied the Excel version when verifying). I think I will just save a copy of the Excel sheet1 as a backup copy (saving the formulas as text, by adding a special character in front like >=. When I need to use the Sheet1. I will copy it back to the Spreadsheet file and find/replace >= with =.

If you want you can use this formula in sheet 1 A2
and then drag it to your other cells

=IF(Sheet2!A2="",Sheet1!A2, IF(Sheet2!A4="", Sheet1!A2,Sheet2!A2+Sheet2!A4))

it should work only if both cells are used in sheet 2 , but not update if 1 or both are empty cells.

Thanks very much.

Thanks again. I did update my profile (Excel version). I use both versions of Excel, it is good to know about newer functions like LET that i am not familiar with yet. I really appreciate all the help/effort.

thanks I did mark as SOLVED now, and I did already click on ADD TO REPUTATION a few days agao.