1094-C part IV - stock sale and mid-year change in Aggregated ALE group

I would greatly appreciate anyone's insight on the below - 

The main question is what all entities are required to be included on part iv of Form 1094-C when a stock sale causes an entity to cease to be a member of one Aggregated ALE Group and become a member of second Aggregated ALE Group mid-year. 

A simple example scenario -  SellCo is one of a number of a wholly-owned subsidiary of HoldCo and is an ALE Members of the "HoldCo Aggregated ALE Group". Mid-year HoldCo sells all of the stock of SellCo to BuyCo causing SellCo to become an ALE Member of the "BuyCo Aggregated ALE Group" (which assume includes other wholly owned-subsidiaries of BuyCo). 

What I am specifically wondering is for the subsequent 1094-C which all entities are required to be listed in part iv of the 1094-C filed by SellCo. (Other Ale Members of Aggregate ALE Group): 

1.  All ALE Members of both the HoldCo Aggregated ALE Group and all ALE Members of the BuyCo Aggregated ALE Group, or 
2. only ALE Members of the BuyCo Aggregated ALE Group. 

I would greatly appreciate anyone's thoughts as I have come up empty handed on this (as well as any additional thoughts on whether this would impact the part III(d) Aggregated Group Indicator reporting.  

There is not a great answer for this question.  I actually wrote how the IRS should change the Form that would allow an employer to provide these details.  You can read my thoughts here - https://accord-aca.com/articles/more-detail-and-further-clarity-required-for-part-iv-of-the-form-1094-c .  If this is still an issue, send me an email and we can try to find a time to discuss over the phone rmoulder@healthcare-attorneys.com .  It is an interesting question.