I like the debut of Diana in World War II, which is now cannon (funny that so may early posts suggested it); biggest head scratcher for me is Steve & Etta who I like in both eras. Here's how I'd put it all together:
0. Amazons travel to Themiscyra in keeping with the Greek lore, and are also immortal.
1. Diana debuts with her Golden Age origin intact, including GA Steve and GA Etta. Steve crash lands on Paradise Island and it goes from there.
2. Diana joins JSA and during wartime fights all her classic foes including Cheetah (Priscilla), and Villainy, Inc.
3. In the closing days of the war Steve is believed dead, but actually time displaced into the future.
4. With the birth of the nuclear bomb, Diana is horrified and returns for a long rest on P.I.
…
5. 20 or so years ago, Diana has a "new" modern origin that brings her back to man's world; essentially the Perez origin minus Steve.
6. In short order she rescues baby Donna from the fire and sends her to be raised by the Amazons.
7. Diana joins the JLA and lives with the Kaepatelis family.
8. She discovers the time-displaced Steve and they reunite. She also meets Etta Candy, a descendent of the original named after her great Aunt from the War.
9. For a TIME the rule that Diana can't return to P.I. is created by Ares, enabling the recent stories.
7. During the course of her modern adventures Donna comes to man's world as a teenager, Barbara becomes Cheetah, Cassie is successor to Donna, and Vanessa becomes Silver Swan.
8. For 5G, Diana and Steve marry and "retire" for a while to P.I. where Lyta is born; when Lyta is a few years old they return to the outside world to continue raising Lyta with Steve as a stay-at-home Dad while Diana adventures.