Seamlessly regroup values for multi-sheet calculations?
 

A workbook with multiple sheets is used to calculate testing data. If all
goes well, the items are tested in groups of five, and all the formulas
across all the sheets are set up to calculate (for example) B3:B7 and
B8:B12. There can be 20 columns of data per item, with each group of five
on each column calculated separately, and those calculated values used
elsewhere. Should the test glitch, though, and one group is only four
items, or all ten are tested but as 3 and 7 vs. 5 and 5, it throws off all
the formulas.

This is a blank "template" file that is opened for each test and saved with
a new name at each use. I've been asked to make changes to the "template"
to seamless regroup the data as required across all the sheets. What should
I be looking at to make sure that if a group has to be regrouped, every
formula calculates only the rows associated with that group across all the
data columns?

(Hope that wasn't too confusing!)
Ed