Hi! I have 2 cockatiels, my first cockatiel, Phoenix my grey male, is now 11 months old. I got a 12 week old Whiteface Pearl Pied a couple of days ago who we called Domino. Phoenix has been interested in Domino only when Domino is in or on either of their cages, his cage being Phoenix's old cage. If Domino is not at one of the cages, Phoenix couldn't care less. But when he is interacting, or trying to, he asks for head scratched from Domino. He occasionally grabs Domino's tail or wing. He has shown zero interest in bonding romantically with Domino and only shows interest to me and any foot he sees with heart wings. He hasn't flirted once, so I don't believe he is trying to mate with Domino like he would with a female. Domino also doesn't like him touching him and has biten him (softly, thankfully) when Phoenix attempts to grab or perch on him. Phoenix has done "the deed" on feet before, so I know he knows how to mate, but when he will sometimes try and stand on Domino, its never in a mating position, but rather stands sideways, usually on the end on Domino's tail. He has met another tiel before and tried to stand on her head, also no flirting behaviour.
Domino is fairly vocal, so we've been learning towards male, as was the pet shop staff (who have extensive knowledge). But with Phoenix's behaviour it has me 50/50 on gender. I also know Phoenix is very interested in other birds and gets extremely excited if he hears another bird on a video on my phone (a favourite of his being Merle the Tiel haha).
Is Phoenix trying to make friends, as he only tries to preen Domino's head or neck and mutual preening is used to establish bond between flock mates and eliminate any anger, or is he just very bad at flirting and I have a female?
I am dying to know what gender I have and as I said, the chattiness of Domino has me leaning towards male a bit more. Can anyone help please? I cannot find any information regarding this anywhere and am so curious.

Note: I have been informed that based on Domino's pattern alone he is most likely male as young female pearls will be covered in pearls and most young male pearls will be scarce in the pattern, such as Domino. He only has pearls on half of his wings and a tiny slither on his neck.