I'm a CPA so professionally I have an elevated interested in these kinds of stories. Based on all the stories I've read over many years I would believe that all of this was done without Ohtani knowing. I can give you a fairly recent example, Dane Cook had $12M embezzled from him by his brother and sister in law.
https://www.cnn.com/2010/SHOWBIZ/celebrity.news.gossip/12/06/dane.cook.restitution/index.html
I can tell you in my own relationship with my wife, I handle the finances. If I wanted to "embezzle" from the family funds I most certainly could do so and she would never know about it. How many marriages do you think are like that? Lots of people trust their friends and family with their money, but they really shouldn't. Trust but verify.