‘Stretch Curve’ command is useful to move geometric objects while simultaneously stretching or shrinking selected lines.
In NX 12, this command was marked as “to be retired”. It was removed from linear menu.
Enabling ‘Stretch Curve’ Command

Continuing to next NX version NX 1847 series, this command remained as “to be retired”.
Starting from NX 1872 series, it was completely removed. But same command can be enabled and used in the NX 1872 series versions using environment variable “NX_SHOW_EDIT_CURVE_STRETCH”.
To enable the command, the user has to set the environment variable “NX_SHOW_EDIT_CURVE_STRETCH” to 1.
Upon setting the environment variable, In the new NX (1872) session, you can add this command to toolbars/ribbon using “Customize” command.
Note
Command was restored in NX 1899 and it was marked as ‘Legacy’.
In NX 1899 series, command can be found using Command finder or linear menu.

Links: NX Documentation | NX CAD Tips & Tutorials