Article 16(4) states:
I suspect that this is the clause that permits/requires this - I would argue that all documentation that is necessary to support the issuing of a certificate i.e. a technical file are relevent
This is not an argument you will win with your notified body.
There should be confidentiality clauses in your NB contract and also the directive is quite clear on confidentiality too. If you want to register your products elsewhere besides Europe, you may struggle if you are not willing to disclose your technical documentation
The notified body shall inform its competent authority about all certificates issued, modified, supplemented, suspended, withdrawn or refused and the other notified bodies within the scope of this Directive about certificates suspended, withdrawn or refused and, on request, about certificates issued. The notified body shall also make available, on request, all additional relevant information
This is not an argument you will win with your notified body.
There should be confidentiality clauses in your NB contract and also the directive is quite clear on confidentiality too. If you want to register your products elsewhere besides Europe, you may struggle if you are not willing to disclose your technical documentation