I know that a PWN is important, however I am not clear if the parent has to request it when submitting a Parent Concern / Evaluation request? Or does the school automatically send it to the parent after reviewing the Parent Concert letter?  Or does the parent submit a copy of their state's PWN form with their Parent Concern letter and ask the school to complete it?  I've done quite a bit of searching and this piece is not clear.  Thank you.  

You do not have to do anything with respect to a PWN, unless you do not receive one when it is required in your state.  A parent concern letter would probably not warrant a PWN, but a request for an evaluation would require either a PWN denying the request or scheduling a Review of Existing Data (RED) meeting to determine if an evaluation is needed.  If after the RED meeting an evaluation is denied, a PWN would be required.  If approved, you would also receive one, along with an attached consent to evaluate form.  The parent does not need to send the form or request one.  But in some cases school districts fail to send PWN's when they should.  In those instances, the parent should reach out and request one.

The parent should really be asking for an eval and not sending a parent concern letter.  Parent concern letters are generally written when a student has an IEP and the parent feels the IEP needs to be updated.

When requesting an evaluation for special ed, the parent should be pointing out the areas of suspected disability which overlaps with areas of parent concern.  This site has a good template for asking for an eval on the last page:  https://www.elc-pa.org/wp-content/uploads/2024/09/Special-Education-Evaluations-2024.pdf

PWN is provided by the school to the parent before (that's where the 'prior' comes in) a school changes or starts or refuses special education evaluations or services.