EXCEL FORMULA

CURTIS775  OK so the problem with that is it depends on how you arrange the sheets (and/or how you name the sheets).  So in the attached I added some Excel 4 macros to the Name definitions which means I had to save it as .xlsb instead of .xlsx and when you open it, you will get prompted that it has macros and if you accept that.  So if you are ok with this then the 'macros' I added are 3 name definitions that return the name of your current sheet (thisSheet), a refence to the same cell in the next sheet (nSheet) or previous sheet (pSheet).  So based on how you added sheets to the beginning  of the book so they go event 4, event 3, event 2, event 1 I used a formula using 'nSheet' to add then new amount to the previous total in the same cell in the next sheet.  This works regardless of the sheet NAME but is dependent on the sheet ORDER (i.e. you can name the sheets 10/4/2020, 9/30/2020, ... as long as the ORDER is Newest to Oldest).  you can easily reverse this using 'pSheet' instead.

An alternative that will avoid the macro complication but will rely on sheet ORDER AND the sheet NAME is to use a fixed sheet name prefix (like you did in that sample book with every sheet called "event " followed by a sequential number.  In this case I added a name definition called "sheetNames" but that could be a fixed cell in the workbook (or just defined in the formula but I recommend against that).   This version is used on sheet called "event 4".