Thanx so much for that link to a solution. I've studied that and it does work.
I also had a reply (via another thread that he was helping me on) from SWS. He suggested the following which also works perfectly for my problem so I thought I would post it here, just in case anyone else has the same deal and needs an alternative solution. This way was considerably easier and saved me having to change my layouts. Just added a timestamp field to my appointments table and it's working!
Hope the following helps someone else.
Instead of taking advantage of 'create records via this relationship' which it sound like that is the way you are doing it, you may instead want to do something like add a button to create a new related record, which runs the following script :
Set Variable [ $parent_id : main_table::id ]
Goto Layout [ appointments ]
Set Field [ foreign_id ; $parent_id ]
Go to layout [ original layout ]
Go to object [ portal object name ] // give the portal a name via the object info box ( or inspector box in 11 )
Go to portal row first
Assuming, you are sorting by something like a created timestamp, which is automatically entered when creating new appointment records.