Hi, thanks for your question. How old is the child and how do you know he is not your biological son?
Thank you. To confirm, you and the mother are still in a relationship and you are fully involved in the child's life?
My name is ***** ***** I shall do my best to help you
AS I understand it your concern is what might happen in the event that you and your wife separate.
As you are aware at that point your wife could use the fact that you are NOT the biological father of the child to have the birth certificate changed which would automatically remove your Parental Responsibility.
In fact it would not be easy to do this without your agreement and co-operation unless she is still in touch with the actual biological father,
There is nothing that you can do about this at the moment - since you are on the birth certificate then adoption is not open to you (and indeed trying to deal with it in this way would be viewed with some concern by Social Services)
However in the event that you do separate you can deal with the matter by obtaining a Child Arrangement Order from the court stating that the child lives with both of you (at different times) which would give you Parental responsibility whatever happens to the Birth Certificate
Please ask if you need further details