Question about Solidcom C1

Hi everybody,
I have an urgent question and I want to ask for advice. Who can help me?

Tonight i have a big event and need to use 8 headsets, I have a set of Solidcom C1 6S and a set of Solidcom C1 4S, can we pair 2 more headsets to the C1-6S to achieve 8 headsets?

This is very important to me.
Thank you guysss