Dan and Destiny have had a business relationship in the past when Dan used to sponsor his stream. For the purpose of this market, I'm not counting a sponsorship as being business partners, though.

If Dan and Destiny invest in real estate together, if Dan's part of the media company, or if they start any other type of business as partners then this market will resolve to YES.

Having concrete plans will most likely be enough to resolve this market, for example "We're buying a high-rise apartment building together and it closes in March, 2024" I would count that. I would argue they became business partners once the plans were concrete, since a lot of businessing takes place before the actual close date in that case.

"I'm going to invest in your media company" but without concrete plans of it moving forward, or any additional details, would not be enough to satisfy this market. 

Destiny and Dan both investing in the same stock, for example if Dan buys Meta, that doesn't count. But if they invested together in the same small business, where both of them have at least a notable ownership stake, that will count. 