Retaining Formula Pairs

I have a spreadsheet where each month we show a set of formulas for the three most current months. To add a new month, I hide the oldest (e.g., April), and insert a column in between the remaining two (May and June). This carries over mappings from some other graphs. I then copy/paste (June) into the new inserted column and change the other one to the current month (July).

When I do this, there is a conversion of the formula mappings for (June). For example,

Cell O5:
=(+'Data'!T6+'Data'!U6)/('Data'!T14+'Data'!U14)

after relocating becomes

Cell N5:
=(+'Data'!S6+'Data'!T6)/('Data'!S14+'Data'!T14)

but I want to keep
=(+'Data'!T6+'Data'!U6)/('Data'!T14+'Data'!U14)

It looks like Excel always assumes that you just want the next thing in sequence in the new cell. But in this case we want unique formulaic pairs, QR then ST then UV. What Excel gives me is QR then RS then TU. There's always a plus or minus one to all the references, even if I update the "Data" sheet first. The only method I've found to fix this is to manually update each set of formulas, which requires a good deal of care across some thirty cells.

Any advice is appreciated!