Enter a custom string at certain points in the document

Hello,

I’m a journalist and I use Scrivener to write articles. Because my work is time-sensitive like to have clearly visible reminders of my deadlines, so I write something like this at the top and bottom of the main “Story” file:

[DEADLINE: 1:00 AM]

where I color-code the time depending on how long I have left.

Is there a way to make it so that, if I change the text at the top of the file, the change gets mirrored in the text at the bottom? Perhaps using custom fields?

Thanks