But think back to S1 and how Logan was treating young William in the park. William was still new to the family and Logan seemed very familiar with the park and the hosts, which makes me think that Delos owned it for a few years before he stepped foot off the helicopter like we saw earlier in S2. That would also explain Logan suddenly dropping out of favor with his father - he asks dad to invest in the park and instead of innovating Logan treats like a playground which gives William the opportunity to overtake Logan on the path of succession.
I think you have the timelines mxed up some. William was married to Logans sister at the time he took him into Westworld for the first time. Logan said as much in the "pitch scene" when William walks away before the presentation, and Logan makes a snarky comment about him and his sister. We know that William gives Jim the pitch to purchase Westworld after he goes to WestWorld for the first time, because of the scene where they see it together and have the dialogue about why Jim should care about this place because he'll be dead before it means anything. In that scene William has a moment with Dolores, to reference their past.
Logan created the moster that Will is today that first time he brought him into Westworld, and once he saw what that type of place can really do to a person and how it helped William gain favor with his father and in the business, it caused him to go into a downward spiral of drugs and depression. (only assuming this because of the scene where he is shooting up with Dolores by him, and he says
“Do you want to know what they’re really celebrating out there? That my dear, is the sounds of fools fiddling, while the whole ******* species starts to burn. And the funniest ******* part, they lit the match. Here’s to you ********. May your forever be blissfully short."