Hey there, Amit, and welcome to planDisney! Visiting the Disneyland Resort with multiple generations of family is so much fun. I'm glad to hear you're planning an upcoming trip for your family!
Theme park tickets are specifically tied to each person, or in other words, only one person can use a ticket and it must be the same person for the entirety of the use of that ticket as seen in number three of the
Terms & Conditions. When you first arrive and scan your ticket at the entry gate, the Cast Member will take a photo of each person that will be tied to their ticket. It would then need to be the same person using the ticket that their photo is tied to for the rest of the trip.
Therefore, it sounds like the best route for your trip will be to purchase a one-day ticket for your wife for the first day. Then you can purchase a two-day ticket for your dad for days two and three. This should get your family covered for a fun few days in the parks!
I visited with my family last July, and although it was pretty hot in the afternoon, we had a fantastic time! We ended up taking a nice, long (and cool!) lunch break in the
Red Rose Taverne in Fantasyland. Depending on the age of your kids, finding a nice air-conditioned spot for lunch can provide a nice afternoon break. Although another option is to cool off by taking a trip down
Grizzly River Run in Disney California Adventure Park!
Thanks again for your question, Amit. I hope you all have a fantastic trip to the Happiest Place on Earth!
Have a Magical Day,
Greg