In the past I've just tried to ignore it and let the cats work things out. Now if she attacked little Jax and was hurting him then I'd intervene but if they're just rough housing then I'd leave them alone. I'm pretty sure that she'll remain the alpha cat and Jax will learn the pecking order very quickly.

If he was more aggressive and alpha like then you'd really have problems but his personality sounds ideal for Paizly. I've also found that it takes females a bit longer to accept new additions and they're much more vocal about everything. My Pearl sure was and she and Ziggy will still sometimes get into growling/hissing matches but it amounts to nothing. It's just a sibling squabble and nothing more. Good luck.