[name]Sister[/name] is having twins sometime in [name]December[/name]. A boy and a girl. They are pretty set on [name]Jackson[/name] [name]Thomas[/name] for a boy and would like to stay with the J letter for the girl. Any suggestions?
If they’re set on a J theme, I can best see [name]Julia[/name] with [name]Jackson[/name].
Now that I think about it, I can also see [name]Julianne[/name].
Other J names that I think feel too formal/classic/vintage with the more modern [name]Jackson[/name], but that they may still like:
[name]Juliet[/name]
[name]Josephine[/name]
Best wishes to you and your sister! 
[name]Julianna[/name]
[name]Jordan[/name], [name]Jordyn[/name]
[name]Juliette[/name], [name]Julietta[/name], [name]Julienne[/name]
[name]Jillian[/name]
[name]Janelle[/name]
[name]Joanna[/name]
[name]Janna[/name]
Some girls’ J names :
[name]Juliet[/name]
[name]Josephine[/name]
[name]Jasmine[/name]
[name]Jacqueline[/name] (although much too close to [name]Jackson[/name])
[name]Jade[/name]
[name]Jane[/name]
[name]Janet[/name]
[name]Jean[/name]
[name]Jessie[/name]
[name]Jessica[/name]
[name]Jezebel[/name] (brilliant name, not so brilliant connotation)
[name]Jocasta[/name]
[name]Joanna[/name]
Jocosa
[name]Jolie[/name]
[name]Josette[/name]
[name]Jovita[/name]
[name]Joy[/name]
[name]Judith[/name]
[name]Juliana[/name]
[name]Jumana[/name]
[name]Julitta[/name]
[name]Juniper[/name]
[name]Juno[/name]
[name]Justice[/name]
Jutina.
And for boys, because I couldn’t resist :
[name]Jacob[/name]
[name]James[/name]
[name]Japheth[/name]
[name]Jasper[/name]
[name]Joshua[/name]
[name]Jonathon[/name]
[name]Julian[/name].
I like [name]Jackson[/name] and [name]Julia[/name]! Since the names will already be really similar with the same initial, I would avoid something like [name]Jessamine[/name] or [name]Jordan[/name] that have the same ending.
[name]Jackson[/name] and [name]Juliana[/name]
[name]Jackson[/name] and [name]Juliet[/name]
[name]Jackson[/name] and [name]Jane[/name]
[name]Jackson[/name] and [name]Jessica[/name]
[name]Jackson[/name] and [name]Jenica[/name]
Is [name]Thomas[/name] a family name? does she have a middle for the girl twin?
I personally like different initials for twins but thats just me.
[name]Jackson[/name] [name]Thomas[/name] &
[name]Jane[/name]
[name]Jaya[/name]
[name]Jillian[/name]
[name]Julie[/name]
[name]Jacinta[/name]
[name]Jessamine[/name]
Jemina/[name]Jemima[/name]
Jaomi
[name]Joella[/name]
[name]Joby[/name]
[name]Jackson[/name] [name]Thomas[/name] would pair nicely with any of these:
[name]Janna[/name]
[name]Jeanette[/name]
[name]Jenna[/name]
[name]Jennifer[/name]
[name]Jillian[/name]
[name]Joanna[/name]
[name]Julianna[/name]
[name]Juliet[/name]
I like [name]Jackson[/name] and [name]Juliet[/name], [name]Jack[/name] and [name]Jules[/name]! Omigosh! I just looked up the meaning of [name]Thomas[/name], and it means “a twin”! [name]How[/name] perfect! [name]Jackson[/name] [name]Thomas[/name] and [name]Juliet[/name] [name]Kay[/name] would be pretty together, and [name]Kay[/name] means “rejoice”.
I really like [name]Juliet[/name], its my favorite girl J name.
Some other ones (sorry for repeats)
[name]Jessica[/name]
[name]Julie[/name]
[name]Julia[/name]
Jupitor
[name]Jade[/name]
[name]Jasmine[/name]
[name]Jenna[/name]
[name]Jordyn[/name]
[name]Jennifer[/name]
[name]Jada[/name]