The user manual of the Sony a7R II does not seem to specify this detail. I have heard different things from various reviews (maybe it changed in a firmware update?) so I'm not sure what to believe.
On a related note, some cameras like the Canon 5D mark 3 and 5DS can be pushed to 7 brackets spaced by 3 EVs using the custom function menu (for a total of 18 stops of dynamic range, from 1/8000 to 30"), and can shift the ISO as well as the shutter speed to prevent extremely long exposures (e.g. 1/8000 at ISO 100 to 4" at ISO 800). Does the a7R2 have a similar capability?