add notes for editors when they edit pages

how can I leave short messages for the editors in each page?

I have contentpart divider plugin installed. this plugin divides the content in the tinymce editor into multiple divs using a code.

each page have itss own template and supports different number of divs, letss say page 3 is divided into 4 divs, page 4 is divided into 2 divs, etc. using the contentpartdivider code.

each page must have the same number of divs as in the template, let`s say: page_id 2 requires exactly 3 divs, no more, or no less, is this does not match, the whole css is messed up,

that`s why I need to leave a message for the editors in each page to know how many divs must have the page, if they accidentally delete a divider code.

for example: this page must use exactly 3 content parts

or more better if it is not too complicated to appear as error message when updating the page and the content parts are not the same as the template requires

to bee more explicit:

the contentpartdivider uses the code: <!–contentpartdivider–> to divide the content

for example in the template I have:

<?php if ( function_exists( 'the_content_part' ) ) the_content_part( 1, array( 'before' => '<div class="txtTop">', 'after' => '</div>' ) ); ?>
<?php if ( function_exists( 'the_content_part' ) ) the_content_part( 2, array( 'before' => '<div id="txtBot">', 'after' => '</div>' ) ); ?>
<?php if ( function_exists( 'the_content_part' ) ) the_content_part( 3, array( 'before' => '<div id="txtImgSm">', 'after' => '</div>' ) ); ?>

this is a template for 3 divs so in the tinymce editor I must have:

the content for the first part

<!–contentpartdivider–>

the content for the secondt part

<!–contentpartdivider–>

the content for the third part