Durning the incident in punk hazard, Law took ceassar as a captive to made Doflamingo resign his título as a Shichibukai.
After Doflamingo resigned being a Shichikai Akainu states in the marines meeting the current Shichibukai: Mihawk, Buggy, Hancock, Kuma, law, Doflamingo and some unknown new one. Who do tu think that is?
My opinion is that Jewerly Bonney is the new Shichibukai since she was captured before the time skip and now seem to be realesed. Also I have a feeling that she is the doughter of big mom but that is just a hunch.