5 axis milling machine with 7i96s

Hi Everyone, 

I am new here and new to CNC, Linux and Mesa boards, so pls excuse the novice questions.

This is my setup
I have a 5-axis milling machine, which uses 2 stepper motors for the z axis, so in total there are 6 stepper motors. I have also bought a servo motor ECMA-C21020RS from Delta to power my spindle. I have a Mesa 7i96s card

Now for my question
Have I bought the wrong Mesa card for my requirement? From my understanding, the 7i96s can only control 5 motors so my 6 steppers and servo exceed the capacity. If so, what would be the best solution? To buy another card and scrap the 7i96 or is there an option to buy an add-on card to work with the 7i96s?

Thank you in advance for your help

I wanted to add that my machine also has a parallel port available, if that would help

You can add a daughter card to the 7I96S parallel expansion port.

You could either use a Mesa daughterboard (a 7I85S would add 4 step/dir axis)
or an inexpensive parallel port breakout, like the common Sainsmart 
5 Axis breakout, either ST-V2 or ST-V3 or the many similar breakouts.