I think they should include Diana Rockwell Trevor story in the movie. She was Steve's mom.
In "Challenge of the Gods", the second arc from Perez, the story is told that Diana Trevor was a US pilot in the WWII, in the "WASF" division (allusion to the WASP, Women Airforce Service Pilots). After the war ended, she became a test pilot and went to test a Sabre Jet. There was a storm and she ended up crashing on Paradise Island. At the same moment, the Amazons were being attacked by a monster trying to escape from Hades through the gates they guarded. Diana went to help and saved Phillipus by shooting the creature, but she ended up dying trying to help the Amazons close the gate. Then she was honoured as an Amazon. Diana was named after her, and the pistol used for the bullets and bracelets were hers. WW costume was based on the colors Diana Trevor had with her (an american flag), and the WW symbol was based on the WASF logo.
They could adapt this story in the movie. The movie could actually start with that. Diana Trevor leaving Steve (who would be around 5 years old) to test the jet, then crashing on the Island, introducing the Amazons. We see the time pass, learning that Diana (WW) sees Diana Trevor as a hero, is inspired by her. After some more scenes on the Island, we go back to grown Steve Trevor, going on a mission on the same location his mom disappeared. Maybe he wants to know what happened, or maybe he is reluctant and afraid. Anyway, when he crashes on the Island, Diana get to know he is Diana Trevor's son and decides to help return him to the outside world.
It's perfect for the way CBMs like to connect everything, not to mention the emotional connection between Steve, his mom, and WW, and the "uniqueness" of a male character having his mom as a motivation (it usually is the father). Also, it's the best explanation there is about why WW's costume is an american flag.