Consolidations Fiscal vs. Calendar year

Hello All:

Here is the scenrio, we have 3 sets of books:

Primary = USD

MRC = MXN

STAT = MXN

We plan to consolidate from MRC to STAT the issue is that the Primary and MRC have a Fiscal Calendar while the STAT has a Calendar year. (July runs 08-JUL-12 to 04-AUG-12)  When we consolidate July the entries from 01-AUG-12 to 04-AUG-12 go to the period of August.  Which is what they originally wanted now they are second guessing this and want to know if we can change the date on the enteries from AUG to JUL? I have tested this and could not updated the Period date only the transaction date,  I believe the only way around this is setup a new SOB for