I assume you already put your sanitized notifications in app/views/layouts/application.html.erb:

<% if notice %>
  <div id="notice">
    <%= notice.html_safe %>
<% end %>

<%= yield %>

if not, you did this now. Now you can make use of them in all views - I guess it’s best practice. All what’s left to do is to send a special param with your link_to method, when needed, here the param name is flash_notice:

<%= link_to 'New Unit', estate_owners_path(@estate, flash_notice: "please keep in mind ...") %>

Simply catch the param in the approriate view (or globally) :) I use flash.now instead of flash as this shows the message only one time and only for the page you were sending the link to.

<% flash.now[:notice] = params[:flash_notice] if params[:flash_notice] %>

With this method you can make your users’ interactions much better, with a few lines of code.

Read more in the official docs: The Flash (flash vs flash.now)