use the Go To Related Record script step and specify the option to show only the related records and match current record only.
I tried GTRR but it is showing 1900 rcords.
In GTRR, I selected from main layout and display on new layout and I checked show current record.
Let me clarify now because I just ran debug, it does go to related record when I start, but when it hits preview mode and pauses, all 1900 records are there. Is there some I need to do before preview and after GTRR?
Assuming this new layout uses the same source table, you could use a variable for this like so:
Set Variable $RecordID = Table::UniqueKey
Goto Layout: New Layout
Enter Find Mode
Set Field Table::UniqueKey = $RecordID
This will isolate the single record without showing all 1900 related records.
Just in case UniqueKey isn't a UUID:
Set Field Table::UniqueKey = "==" & $RecordID
Oh, and I'd also enter find mode before switching layouts, so you don't unnecessarily load whatever record happens to be showing in browse.
Small nitpicky things, though. Hope they're helpful.
Thanks for the improvements Chris, didn't consider the data load.