I would like to put all the related notes onto a print layout.
when printing related records from a portal in nearly any version of Filemaker, it's often best to switch to a layout based on the portal's table and use list view with fields from the parent record placed in headers and summary layout parts. That's how the invoices starter solution prints out the line items for an invoice if you want to see an example.
Whether you use a portal or all the notes combined in a single field, you are up against an upper limit set in the design of your layout. You can only set a very large size to the field or portal and set it to slide up and resize the enclosing part, but you can't expand the size of the field or portal. Once you get so much data that it no longer "fits" the extra data won't show.
That said, you could use a script that loops through the related records to merge all the notes data into a single field:
IF [Not IsEmpty ( Notes::ForeignKeyField ) //check for related notes records]
Go To Related Record [Show only related records; From table: Notes; Using layout: "Notes" (Notes)]
Set Variable [$NoteList ; value: $NoteList & ¶ & Notes::NoteText ]
Go To record/request/page [next ;exit after last]
Set Field [ParentRecord::NoteList ; Right ( $NoteList ; Length ( $NoteList ) - 1 ) ]
Go to layout [original layout]
Use your actual table and field names in place of mine. I'm assuming that FM 8 supports variables. If not, use a global field in place of the variable.