As AndyStaples said, it is usually done the other way round, making the morphs in the conformer automatically react to morphs in the character. That is called "super conforming", and if there is no pressing reason not to, I would recommend that you do it that way. However given some preconditions, it should be possible to have the character react to morphs in the conformer by applying a pose file to the character to inject appropriate slaving code.

Assuming that there is a  morph with the internal name "BellySize" in both the conformer and the character, you could apply a pose like the one below to the character to add the necessary slaving. The character would need to be the first figure loaded into the scene, and the conformer would need to be the second figure loaded. This is necessary so that the conformer ends up using the same figure number as in the pose file ":2". {

version
        {
        number 4
        }

actor hip
        {
        channels
                {
                targetGeom BellySize
                        {
                        valueOpDeltaAdd
                                Figure 2
                                hip:2
                                BellySize
                        deltaAddDelta 1.000000
                        }
                }
        }

actor abdomen
        {
        channels
                {
                targetGeom BellySize
                        {
                        valueOpDeltaAdd
                                Figure 2
                                abdomen:2
                                BellySize
                        deltaAddDelta 1.000000
                        }
                }
        }
}

To use it you would load the character, load the conformer, conform it, select some part of the character, then apply the pose. If the BellySize morph needs to be injected into the character, you could put the morph in the same pz2. If the internal channel name is different, eg "targetGeom PBMCC_07" for example, just use that name in the code.