You can find this info easily enough on the website.
During the preemption sale you need 1 membership card for each ticket you want to buy. So essentially, you'll be able to get one for yourself, not for your dad.
Sorry, It might just be me but I find the preemption information on the Juventus - Inter page om juventus.com to be confusing and contradicting for a premium member not living in Italy. First it says:
"- Only J1897 and Premium Members physically in possession of the membership card can buy tickets in pre-emption mode only if they are physically hold the Supporter card and other 3 tickets only if also these 3 fans hold a J1897 or Premium Member card
- The J1897 and Premium Member card holder not resident in Italy, can buy tickets on Listicket.com inserting in the promotional space the Member Card number; we remember to select Home Ticketing and print at home your ticket"
So is the first paragraph for international premium members also or only for Italian members?
Then further down under the section J1897 and PREMIUM MEMBER PREEMPTION SALES it says:
"Through these channels, every J1897 and Premium Member may purchase up to 4 tickets as long as they have been registered J1897 or Premium Members or premium Members not Italian resident since 1 July 2012."
So, from the information above, can I buy 3 or 4 tickets and do all ticket holders need to be premium members or is it enough if the one buying the tickets is a premium member?
This probably won't go well so I expect I'll have to resort to paying a fortune and get tickets through a secondary market instead.