Help creating dynamic refrence cells
 

I need to reference a dynamic cell on one spreadsheet (ss) within another ss.
example:

On ss1, I want to display a single cell reference from ss2 that constantly
changes when adding or subtracting records

ss2 has this as a reference: E89=SUBTOTAL(9,E2:E87)

BUT, here is the problem! What if I add 6 more records to the total dataset
within ss2 thus changing the dataset reference to E95=SUBTOTAL(9,E2:E93)? Now
my reference cell in ss1 is displaying #REF!

How do I get the ss1 reference cell to automatically follow the SUBTOTAL
cell to the data within ss2 as it changes?