Because this forum is for legal questions, I can only tell you that it is not illegal to do so. Having said that, I have absolutely no idea what sort of answer you might get to the same question posed to a social worker, minister or mental health professional.
The information provided in this answer is only general shall not be deemed to create an attorney-client relationship.
That is fine. It is not illegal. However, you want to make sure that the mother is OK with it as well as your wife.
The information provided in this answer does not create an attorney-client relationship and is not considered to be legal advice.
I like Mr. Leroi's viewpoint here. I agree with him completely. Of course, dare I ask how your inability to communicate directly with this woman is impacting your child? I hope that's smooth!!
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.