My name is ***** ***** I am a NSW Solicitor. Thank you for your question, and will do my best to assist you with your question. Please understand this is not legal advise Please understand this is not legal advice but a guide to assist you.
If you go down this path then the court may make orders that he see his son.
In order for him to have a DNA test you have to contact him and if he refuses then you have to go to the Family Court.
If you do not wish him to have contact I would suggest you do nothing at present and wait until your son is older and the current partner has her child and then make contact with her.
If she is underage he has committed a criminal offence and the police can charge him.
There is no law though that says a child has the right to know their siblings.
Also as he is the father of your son, if you decide to go to court and have him tested you can also claim chid support for your son.
I hope this makes sense and is of assistance. If there is nothing further
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