This applies to the Liquid Channel
With a standard analogue compressor, when 'Link' is switched in, a diode circuit ensures that whichever channel requires the most gain reduction controls the action of both compressors.
This way the situation where one channel is more compressed than the other is avoided. The Liquid Channel works in this way too but it is possible to link up to eight of them.
Also, it is possible to disable the control linkage but to still have the action of the compressors linked. This allows you to set individual ratios, thresholds etc. whilst the gain reducing action of all of the compressors is still linked.