Report - code builder

Here's a .jpg to help explain my problem better

the Report is supposed to show the Total Income for the period entered. My problem is with the Addendum (Act aditional in the report), since it's linked to the Contract and i need to show the contract info for that addendum, but i also have to show contracts info.

The problems appears with addendum for 2012 which have a contract done in 2011, because the info from 2011 appears in the report and affect the sums.

That is why i was trying to resolve this by code.