http://www.marinedepot.com/md_educationcenter_species.html
One more compatibility chart.
Many people keep bluelines and emperors together. I’ve seen a pair of both on the same tank. I don’t think you’ll have a problem especially since they’re two different genus chaetodontoplus and pomocanthus. I wouldn’t add a larger emperor though, they’ll be a lot more aggressive then a blueline. I’d add a large juvenile that’s been thru QT, healthy and eating aggressive. Also there will always be some aggression especially with FOWLRS, its just when it gets beyond a pecking order and fish are getting hurt is when its time for a change. Tail fanning or a little chase here and there is normal.