Upgrade VC-link from 40G to 100G on 4-member QFX5110

Hi,

I have a 4-member VC of QFX5110-32q up and running Junos 17.3R1.10 flex.

Right now, the VC-ports are 40G and I want to upgrade these to 100G instead.

Questions:

1. I think I cannot mix different speed for vc-ports within a single VC right ?

2. Is there a smooth way to upgrade these VC links or will I have to stop the stack anyway and interrupt traffic ?

Thanks.

Best,

G