custody battle with siblings

[Desire]

Can my ex ask the courts for my son (20 yrs old) to be put on a custody order NOT to be around his sister? He has no reason to not be. My son is a college grad that is going into the navy and very upstanding man. My ex does not want him around our daughter and is asking the courts NOT to allow him to communicate with his sister...Is there a Law that keeps siblings together?

 

[army judge]

Can my ex ask the courts for my son (20 yrs old) to be put on a custody order NOT to be around his sister? He has no reason to not be. My son is a college grad that is going into the navy and very upstanding man. My ex does not want him around our daughter and is asking the courts NOT to allow him to communicate with his sister...Is there a Law that keeps siblings together?

Custodial parents have the right to keep others from seeing their charges.
That said, siblings, especially adult siblings have no inherent right to visitation or contact.
The kid is going in the navy, I suggest he focus on that, and you not encourage him to make mom mad.

 

[Proserpina]

Can my ex ask the courts for my son (20 yrs old) to be put on a custody order NOT to be around his sister? He has no reason to not be. My son is a college grad that is going into the navy and very upstanding man. My ex does not want him around our daughter and is asking the courts NOT to allow him to communicate with his sister...Is there a Law that keeps siblings together?

No, there is no such law. Now why is it that your ex doesn't want your son - I assume he isn't your ex's son? - around your mutual child?