Edit MT4 EA to backtest

I have an existing MT4 EA that calculates the normalized data from 2 currency pairs and trades off that data. It's a very simple EA that buys one currency pair and sells the other currency pair based on the absolute difference of the normalized data. One problem I face is that I am not able to backtest this EA because the backtest only reads data from one currency pair while in actual fact we need to read data from 2 currency pairs (which is how the EA trades). I would need to work around this. I think we can create a script that normalizes the years of historical data i have for each currency pair. Then when the EA wants to do a backtest, it just needs to pull the relevant data from the correct currency pair. Willing to discuss other ways around it.