I told to chatgpt to write me a trip plan in detail, this is its answer:

Day 1:

Arrival in Istanbul in the afternoon.
Check in to your hotel and take some time to rest.
In the evening, you and your brother can visit the Galata Tower and explore the streets of the Beyoglu area.
Your parents can visit the Istiklal Street, which is a popular shopping destination in Istanbul. There are many shops and boutiques selling a variety of items, including clothing, jewelry, and souvenirs. They can take the M2 metro line to Taksim station to reach Istiklal Street.

Day 2:

All four of you can visit the Blue Mosque and the Hagia Sophia. These two landmarks are located near each other in the Sultanahmet neighborhood.
Your parents can then visit the Grand Bazaar, which is one of the world's oldest and largest covered markets. There are thousands of shops and stalls selling a wide variety of items, including clothing, jewelry, spices, and more. They can take the M2 metro line to Beyazit-Kapali Carsi station to reach the Grand Bazaar.
You and your brother can visit the Istanbul Archaeology Museums, which are located near the Hagia Sophia. The museums consist of three separate buildings and feature exhibits on ancient civilizations from around the world. You can take the T1 tram line to Gülhane station to reach the museums.

Day 3:

In the morning, all of you will attend the visa appointment at 12:00 noon.
Afterward, your parents can visit the Spice Bazaar, which is a popular market selling a variety of spices, teas, and sweets. They can take the T1 tram line to Eminönü station to reach the Spice Bazaar.
You and your brother can visit the Topkapi Palace, which was the main residence of the Ottoman sultans for nearly 400 years. This site features a variety of exhibits, including weaponry, ceramics, and Ottoman costumes. You can take the T1 tram line to Sultanahmet station to reach the palace.

Day 4:

Your parents can visit the Nişantaşı neighborhood, which is known for its high-end shopping and dining options. There are many luxury brands and boutique shops in this area, as well as cafes and restaurants. They can take the M2 metro line to Osmanbey station to reach Nişantaşı.
You and your brother can visit the Chora Church, which is known for its well-preserved Byzantine mosaics and frescoes. You can take the T1 tram line to Edirnekapı station to reach the church.
You can then visit the Istanbul Modern Art Museum, which features exhibits on contemporary Turkish and international art. The museum is located in the Karaköy neighborhood, and you can take the T1 tram line to Karaköy station to reach the museum.
Your parents and you can meet up in the afternoon and visit the New Mosque, which is located near the Grand Bazaar. The mosque features stunning architecture and intricate tile work. You can take the M2 metro line to Vezneciler station to reach the New Mosque.

I hope this more detailed explanation helps. Please let me know if you have any further questions or if you need any further assistance.