Changing the data rate of Receiver in GXB

Does anyone know if it's possible to reconfigure the data rate of a GXB receiver only implementation in ARRIAII GX. :confused:

The CDR changes as the data rate is changed but I think I may need to change the reference clock the GXB is expecting to help it lock.

I have two expected data rates 2.7Gbps and 1.62Gbps. I have two reference clocks that I can provide to the GXB block (108MHz 2700/108 =25 and 162MHz 1620/162=10). So when the data rate changes I connect the 108MHz clock or the 162MHz clock. I think this would be ok to do if the 108MHz clock was 270MHz i.e. 2700/270= 10. This means the factors would be the same. Since the factors are not the same and it's difficult to make them the same I thought I might be able to tell the GXB that I want to use different factors by reconfiguring the data rate and expected clock. Does anyone know if this works? I am really struggling to decipher the documentation because it just keeps talking about the TX data rate.

Thanks

C