Formula will not auto update when sheet is protected

I am working with a sheet that has a subtotal at the bottom of a column. When I want to add data, there is a macro that inserts a new row, but when I add the data, the cell that shows the total for the column does not update to include the new row.

For example, the formula in the subtotal column is this:

=SUBTOTAL(9,G7:G26)

When I insert a row, if the sheet is unprotected, the formula will update to show:

=SUBTOTAL(9,G7:G27)

When I insert a row, if the sheet is protected, the formula does not update.

If I unprotect the sheet, the formulas are likely to be tampered with, and if I only unlock that one cell, that one may be altered as well. Can I do anything that would allow the sheet to remain protected, but update the formula when new data is entered?

Also, any other suggestions for the layout or design of this sheet would be great. I'm still learning a lot about excel. Thanks for any help.

--One more thing, I did add validation to the cell as suggested in another thread, and left the cell unlocked, but discovered that if I hit the "Delete" key when the cell is selected, it clears the formula.