Husband and Wife each have their own SDIRA

[Account Closed]

I've already contacted 2 custodians on this matter and one says it's ok and the other says contact a CPA or lawyer. I've reached out to both but figured I'd ask here too.  I know it's a confusing subject so I'll try to illustrate it below. We haven't done this yet, just trying to make sure we don't do anything that is considered a prohibited transaction.

A) Brother's SDIRA and Sister's SDIRA buy rental property A together. This is not a prohibited transaction. 

B) Brother's SDIRA and Brother-in-Laws (Sister's husband) SDIRA buy rental property B together. This is not a prohibited transaction.

I know that we can do either A or B alone and it would be ok. But the question is can we do both A and B as long as the husband and wife's SDIRA's are not involved in the same property together with the brother's SDIRA?