Hey Mate
Generally all kites run off a system where as long as the line length of the 4 /5 lines is all the same then you are sweet to go.
The line length is the most important thing as this sets the power differential on the kite.
If the back lines are two short you stall the kite.
Using another bar or even one bar will make no difference unless you are talking about a small bar for both a 7m and 11m. The difference then is a short bar makes kite turn lower.
Hope this helps out.