I have twin characters that I’ve had difficulty with for naming in the past few weeks.
Backstory: They were born as siamese twins; having operation to separate them due to not being able to function properly and they got prosthetics for their missing limbs, which nobody knows about except for the surgeons and their father. After the operation, they were raised in a facility that experiments on a very interesting subspecies of humans but they were treated mostly better than other victims in the facility since their dad owned it.
Character Description: The twins have strawberry blonde hair and light brown eyes. They’re M/F twins. The female twin is more overbearing and brash while the male twin is shy and almost always quiet, but can be creepy. They’re 14 years old.
Who named the character: The mother wanted to name the female twin [name_u]Sandy[/name_u] (that’s all I could come up with names) but the father named the twins himself.
Already Considered: I’ve considered [name_f]Lily[/name_f] for the female twin but it sounded way too out of personality for her and I’ve considered [name_m]Boaz[/name_m] for the male one but I wasn’t sure about it.
[name_m]Don[/name_m]'t Suggest: Please don’t suggest me names that are “classical” like [name_f]Margaret[/name_f], [name_m]George[/name_m] and [name_m]Phillip[/name_m] and no names that begin with Z, X or Y.
Other: Generally I want names that sound a bit soft for the male twin (like [name_m]Boaz[/name_m]), and either female or unisex names that sound strong for the female twin.
Thank you for your time reading this and I hope this isn’t too much to ask for! If you need any more information, please ask me! 
I like [name_m]Boaz[/name_m] a lot! What about just [name_u]Bo[/name_u]/[name_u]Beau[/name_u]?
[name_u]Arlo[/name_u]
[name_m]Ezra[/name_m]
[name_u]Theo[/name_u]
[name_u]Rowan[/name_u]
[name_m]Hugo[/name_m]
[name_m]Harry[/name_m]
[name_m]Orin[/name_m]
[name_u]James[/name_u]
[name_m]Leo[/name_m]
[name_m]Eli[/name_m]
[name_m]Milo[/name_m]
[name_m]Connor[/name_m]
[name_m]Adam[/name_m]
[name_m]Wesley[/name_m]
[name_u]Emory[/name_u]
[name_u]Luca[/name_u]
[name_u]Ollie[/name_u]
[name_f]Hazel[/name_f]
[name_f]Lola[/name_f]
[name_f]Edie[/name_f]
[name_f]Olive[/name_f]
[name_f]Iris[/name_f]
[name_f]Nell[/name_f]
[name_f]Kate[/name_f]
[name_u]Ashley[/name_u]
[name_f]Anna[/name_f]
[name_f]Caroline[/name_f]
[name_f]Lucia[/name_f]/[name_f]Lucy[/name_f]
[name_f]Violet[/name_f]
[name_f]Nora[/name_f]
[name_u]Quinn[/name_u]
[name_u]Sacha[/name_u]
[name_f]Elsie[/name_f]
[name_f]Sadie[/name_f]
[name_f]Isla[/name_f]
[name_f]Ava[/name_f]
[name_f]Eve[/name_f]
[name_f]Molly[/name_f]
[name_f]Clara[/name_f]
[name_f]Hattie[/name_f]
I don’t know if this matters but it’s actually impossible for there to be boy-girl conjoined twins. Conjoined twins are genetically identical, which means they must always be the same sex. I’m sorry if it puts a wrench in your story, but the idea of boy-girl twins with unknown body modifications being tested on in a facility is still very interesting.
As for names, feel free to mix and match:
[name_u]Dorian[/name_u] and [name_f]Patricia[/name_f]
[name_m]Alvin[/name_m] and [name_u]Dana[/name_u]
[name_u]Ashley[/name_u] and [name_u]Alexis[/name_u]
[name_m]Carver[/name_m] and [name_f]Caitlin[/name_f]
[name_m]Marcel[/name_m] and [name_f]Maxine[/name_f]
[name_m]Nolan[/name_m] and [name_u]Bristol[/name_u]
[name_u]Avery[/name_u] and [name_f]Matilda[/name_f]
[name_m]Marshall[/name_m] and [name_u]Tatum[/name_u]
[name_m]Joel[/name_m] and [name_f]Kirsten[/name_f]
[name_m]Mathew[/name_m] and [name_u]Mason[/name_u]
[name_m]Clay[/name_m] and [name_f]Crystal[/name_f]
[name_m]Arthur[/name_m] and [name_f]Antonia[/name_f]