I think you have to create new account anyway. At least that’s what I did for YouTube Music. Because I don’t want to change home country of my main account and I even think you can only change country once a year or something, so I created new one, using VPN set to Turkey, and now I have family pack for around 1.20€ - 1.80€ (this month it was 1.20€), up to 6 users. But this is only YouTube Music Premium, without YouTube Premium.
I think you have to create new account anyway. At least that’s what I did for YouTube Music. Because I don’t want to change home country of my main account and I even think you can only change country once a year or something, so I created new one, using VPN set to Turkey, and now I have family pack for around 1.20€ - 1.80€ (this month it was 1.20€), up to 6 users. But this is only YouTube Music Premium, without YouTube Premium.