“The North Korean press did not say which department Yeo-jong is in charge of, but officials here believe the post must be fairly important.”
I read fairly recently (within last 6 months or so) that she has been given the keys to the purse, that she is in charge of major financial dealings for the Worker’s Party and also (obviously) the Kim’s private stash and perhaps control of many other funds.
There was indeed such a report.
She probably has put in place a "If something unfortunate happens to me" plan.