The basic rule of thumb is that you never want to double up on any zone/area on country. No Forex correlation charts area needed for this.
For example, if you normally risk 3% per trade, then you would not want to risk 3% on the EURUSD and EURNZD each at the same time.
BUT if you could really not pick between them and really loved them both, what you could do with the JPY pairs for example is if one forms something, they all form it, then instead of just picking one, you could play both trades but split your risk.
For example, you could play both the EURO trades above but instead of doubling your risk, we could risk 1.5% on one trade and 1.5% on another, so we are still risking 3% overall. This avoids us risking and losing 6% of our account to the EURO if something happens in that region.
There is a video lesson on how you can do this in your trading at; Trick to Trading Multiple A+ Trades in Same Forex Pairs & Never Risking TOO MUCH
You can also find a list of Forex pairs and markets to trade here.