HDL Coder Zedboard example led_blinking_4bit: Port-width of LED-Interface

I am trying to make a custom reference design for the Zedboard for use with HDL Workflow Advisor.

My goal is to extend the existing reference-design for the Zedboard such that I can control 4 of the 8 LEDs by switches.

I would then like to control the remaining 4 LEDs by the HDL-Coder-Example led_blinking_4bit.

However it seems, that the generated ip-core has a port-width of 8 bit and such controls all 8 LEDs (the upper 4 are always off) even if the LED signal is only 4 bit.

Is it possible to use only a part of an IOInterface and use the remaining part by another block?