In-Law Attribution

Would appreciate a quick sanity check here:

Mother owns 70% of Corp A. Mother has an adult daughter, who is married to son-in-law. Son-in-law owns the other 30% of Corp A. Son-in-law also owns 100% of Corp B. (Assume no other attribution aside from family, no excluded interests, no ASG, no management group, not a community property state.) 

Under 1563, I believe that mother will not be deemed to own any stock in Corp B. Daughter would be deemed to own all 100% of son-in-law's stock in Corp B, but because daughter is an adult, and mother does not own >50% of Corp B, mother is not deemed to own daughter's (attributed) stock in Corp B. Also, the prohibition on double-attribution among family members would cut off deemed ownership of those shares with daughter (i.e., once they are attributed from son-in-law to daughter by spousal attribution, they cannot be attributed again to mother, even if mother did own >50% of Corp B). 

Likewise, as an adult, daughter would not be deemed to own mother's shares in Corp A because daughter does not own >50% of Corp A's shares. 

Because mother owns >50% of Corp A, she would be deemed to own any shares in Corp A owned by daughter directly (zero); however, the double-attribution rule would prevent attribution from son-in-law to wife to mother, so mother would not be deemed to own son-in-law's 30% in Corp A.

I think I'm left with:

Corp A: 70% mother; 30% son-in-law; same 30% daughter through spousal attribution

Corp B: 100% son-in-law; same 100% daughter through spousal attribution; 0% mother

This leaves only 30% common ownership, which clearly avoids a controlled group unless I am missing something.    

I would agree that looks correct with what you've laid out with respect to 1563.

You are correct, no CG, but make sure it's also not an ASG before designing separate plans.

Thank you both for confirming my thinking. CuseFan, neither company is a service organization, so we're clear on that side as well.