Import the PDF once into the container field of a single record. Then link this record to all 50 records of your current table in a relationship.
That's the basic concept behind a relational database--use relationships to link to the same data so that you don't have to create multiple duplicates of the same data.
I think I am missing something. So the container field I am talking about is in a portal on each of the records because it's actually belonging to another table all together. That table is linked to the main record table through a unique ID (so each record could have a different file if I wanted that).
I attached a pic so you can see what I mean. The ERD is highlighting the table with the container and the layout is showing the portal that contains this container. They are connected by the unique ID.
What I can't tell from your screen shot is whether Documents Table RP::_ID uniquely identifies a record in the Documents table or your layout's table.
But it doesn't really matter because this appears to be a many to many relationship. A record in your layout's table needs to be able to link to many Documents and a record in your Documents table may need to link to many records in your layout's table. (Your Screen shot doesn't show the name of your layout's table.)
A many to many relationship would be implemented with these table occurrences and relationships:
Layout::__pkLayoutID = Layout_Document::_fkLayoutID
Documents::__pkDocumentID = Layout_Document::_fkDocumentID
You can place a portal to Layout_Document on the Layout layout to list and select a Documents record for each given Layout record. Fields from Documents can be included in the Portal to show additional info about each selected Documents record and the _fkDocumentID field can be set up with a value list for selecting Documents records by their ID field.
So you would insert the PDF once into Documents, but you would create records in Layout_Document to link your "50 records" in the Layout table to that newly inserted PDF.