Maybe an old question, how to use one EA manage two or more trades for two or more currency pairs?

You're right. Its an old question.

A very quick use of the search function above *shock* yielded the following result.

' How to run EA for multiple pairs?'

CB

And to save another search in a few day's time: you can't backtest something which trades multiple symbols. The strategy tester requires you to pick a single symbol to test against, and the EA can only see prices and place orders for that one symbol.

You're better off trading "current pair" and attaching it to every chart you want.