However, as always there are multiple ways to mitigate UBIT.The most important compliance concept to be aware of is prohibited transactions.

@Ken NeusaengerYour strategy has several issues with respect to IRS guidelines.In exchange for tax-sheltered status in an IRA, the IRS rules prohibit any direct or indirect benefit, in either direction, between you and the IRA.Simply from the starting point of you buying a parcel personally and having the IRA buy the rest, you have introduced risk.Any services associated with the property must be performed by an unrelated 3rd party. 

Of course, then you won't have anything leftover to cover any damages, which is why most leases prohibit tenants from using it as payment for the last month's rent.

There are no rules in the Act that prohibit an investor from generating income and net worth.

It sounds interesting but potentially cost prohibitive or not having a great return for the cost of the adu build.Do you have any examples or know of anyone that has purchased a sfh and built an adu successfully for cash flow?

While there are rules that need to be followed we didn’t find them prohibitively difficult to navigate.

While under certain circumstances it might be possible to create a partnership between qualified plan and disqualified person there is always likelihood that  such arrangement may lead to a prohibited transaction.

is brother consider a disqualified person on IRA transaction?

You will want to avoid prohibited transactions.

The biggest risks financially would be that you buy into a condo association that issues a special assessment in the future or starts prohibiting rentals.