Yes, what will happen is they will have to sign a release and the records will then be sent to the reviewing doctor and then should be included in the records that are on hand for that person.
It will required to be disclosed as the person will need to sign a paper saying they have not had any other medical issues since their initial medical review or whatever terminology they use.
Failure to disclose prior to OCS could result in a variety of actions down the road which could be a small delay while being cleared up, to being sent home from OCS, the faster the issue is disclosed the quicker it can be resolved.
I have been through this with an applicant, not specifically psych doc, and it resulted in the OCS date being cancelled just a few weeks prior to shipping, the issue was resolved in a few weeks then had to get a new OCS date which took another 6 weeks I believe. If he had disclosed when it happened he would have kept his original date.