Sibling private parts game

I have two children, a boy- 6 & a girl- 4.  6 months ago my son knocked a girl at school down & tried to bite her between the legs, but instead bit her inner thigh.  We watched a dinosaur movie a few days before, in one scene a t-rex knocks another dinosaur down & starts to eat, starting with upper thigh.  Believing this was his imagination roleplaying the scene, we apologized to the family thoroughly, punished my son for biting & explained the severity of his actions.  (he has always been a biter but after 18 months it was on VERY rare occasions - approximately once every 6 months to a year)
Months after the school incident, my husband & I separated, the kids and I moved countries to be closer to my family.  We have been away from my husband for almost 3 months & in the last week and a half my son chose to lure my 4 year old niece away from a family gathering for 2 minutes.  In this time he asked her to remove her clothes & lie down, he bit her in her 'private' area.  She immediately came to tell her mom, she was visibly upset wondering why her mom hadn't protected her & why would my son do that?  All the adults were devastated & shocked, none of us has dealt with anything like this.
Since the incident with my niece, my son has not left the house & has increased his drive to touch himself & female nakedness, especially with my 4 year old daughter.  I tried to speak with my son about anyone touching his 'private' areas, taking pictures, etc., but he says no one ever has.  I explained it's not healthy for them to touch each other or see each other naked, and it's become nearly a full time job.  My son & I are waiting to hear back from a counsellor about my concerns but due to the increase of interest from both my children I don't know if we can wait.  
Should I be doing more?  Do I need to stay patient?  Should there be punishments?  My kids don't know anyone here but their cousins (who they can no longer visit), I can't separate them to slow this process down.

[familyfriend]

Dear Blue, I am so sorry for your predicament.  You must feel so isolated.  Maybe there is a group you can join, or some kind of counselling for you.  Divorce is hard enough, but when there are issues with a childs behaviour to boot and then you are segregated by your family because of it.... you are in my thoughts and prayers.


hugs