Verizon is a holding company. It's structured as a holding company with numerous subsidiaries because it's got physical property all over the country, and is subject to literally thousands of different regulatory regimes: federal, 50 states, thousands of city and county utility boards. But its profit figures are reported on a consolidated basis. (And if you have hard evidence to the contrary, man do you have a valuable lawsuit on your hands.)
It's setup in slightly different ways for different niches in the market, but on the mobile side it's a holdover from original FCC regulations on how ownership of spectrum worked. The FCC wanted to encourage competition, so they heavily emphasized partnerships with little mom and pops for each local region of spectrum. After the FCC removed those regulation requirements, those partnerships were still useful as sort of bellows of profit so that the C level can manage their growth curve.
This is all not really private information, is how pretty much all of the telecoms are structured, and isn't illegal.
Not the other 30% or 49% or what have you that's not owned by the national company. But the nature of how the national company handles so many services for the partnerships means that 'negotiations' can change how the money flows around year after year in a way thats controlled by the national company (I say national company because they really are more than just holding companies, they handle large pieces of the business as well).
The profit that accrues to those partnerships either never gets back to Verizon (in which case how is it relevant?) or simply "bellows" (as you put it) the cash flow to Verizon. In the latter case, it'll still show up in long-term measurements. But at the end of the day, Verizon's 5-year profit margin is 13% while AT&T's is 11%. That's about the same as Starbucks. Google and Apple are at 20%+, and Facebook is at 28%.