Family member/self directed IRA

[Chase Gochnauer]

Hello My stepfather has interest in investing in an apartment building I'm purchasing via a second mortgage for a portion of the down payment for a fixed return. We determined that a self directed IRA was the best vehicle to accomplish this, but then I came across the 4975 rule that calls a lineal descendent a disqualified person. Is anyone aware of any way around this? Technically we are not blood related, but I would be a part of the estate one day since he is married to my mother which I think would classify me as a lineal descendent? My CPA is checking into this also but it's a bit uncommon of a situation. Thanks!