When selecting an import object in the Import or Add Coordinate Systems Dialog where the individual items of the import are to be added manually (either control or multipoint transform), an empty external geometry object is shown on the list.
To create a new item in the object, select the new object at left and use the ‘New...’ button on the right hand side of the Imports and Coordinate Systems Pane to manually enter the external measurements (a new item for the multipoint affine object is shown here):
When adding new points/coordinates, the name of the point and its coordinate position and units are added:
If copying a coordinate from another application or file, it can be pasted using the ‘Paste coordinate…’ button, if it’s in comma or space separated text format.