Universe Today came with ethe following article of directly imaged extrasolar planets :  
http://www.universetoday.com/133087/four-planet-system-directly-imaged-motion/
Using  the data and orbital data of the planets from here  
https://it.wikipedia.org/wiki/HR_8799 , I made this sim of the system  
 
Not suprisingly there is a strong gravitational influence between the planets ( which should have a 1:2:4:8 resonance ) , resulting in modified orbital paths after a couple of orbits .