PSN (primary) -> PC account merge, which email?

[Druzhir]

I have an old pc account that i spent some plat on, and a more recent ps4 account that has much much more progression.

I can log into the pc account, but the email attached to it is a dead email i can't recover or log into.

I want to merge the two accounts, the ps4 account being the primary account, but I don't know which accounts' login info will be used.
If I have the ps4 account as the primary account, will that make that email the main login email, or would it still be the old pc one?