top heavy - aggregation

[Guest Laura A]

Company A buys three different Physician Practices, B, C and D. All 3 practices had their own plans. B terminated/distributed its plan. C froze its plan. D merged assets into Company A's plan. A, B, C and D are an affiliated service group (B, C and D are participating employers in A's plan).

Which plans (if any) should be aggregated with A's plan for top-heavy? I'm hung up on the whole "sponsored by the employer" thing, since B, C and D's plans were never sponsored by A and really wouldn't be considered A's plans. My thinking is that you would include D (since the assets are now part of A's plan anyway), but not B and C. Am I totally crazy, or is there something else I should consider?