MT4 Bug Fix : Close by certain magic number

I have a job offer to fix my MT4 EA. The main problem is : It interfere the other EA orders ( close them )

My suspect is my previous EA programmer was not manage its magic number correctly, hence it close other trades 

Solution needed for this job :

1. Carefully review all the code, and inspect for any potential error

2. Fix the close all trades & fix the magic number issue by make sure my EA only close the trades relevant to its magic number

    My suspect : This ea has a feature to close all order in friday and when it reach certain profit. Maybe it reads from the trade terminal but ignoring the magic code.

3. Add feature : close all order when DD = .. %

4. The final fixed EA should be MQL5 compliance ( I will check in MQL5 marketplace )

Challenge :

1. My EA is a multi currency EA ( attach in 1 pair, it can manage to trade several pair as on the setting )

2. My EA can not be back-tested

3. Line codes about 1600 

My expectation :

1. You're a proactive, communicative and diligent programmer 

2. As my EA can not be back-tested, the potential issue might recognized later after this job closed, in this case you should provide help and support to the related issue. 

3. I prefer quality job rather than speed. Hence I will spare up to 5 days