What KIND of calligraphy? The square-tip nibs used for italic writing are completely different from the pointed flexible nibs used for variable line widths.
What is usually marketed as a "calligraphy set" is a cartridge fountain pen with one or more crisp italic nibs, or sometimes a dip pen with Speedball lettering nibs.
Occasionally, though, I see "calligraphy sets" that are dip pens with one or more flexible nibs.
If your relative wants a fountain pen with a flexible nib, you may have to find a vintage fountain pen from which to obtain the nib and feed. If it's an italic that's desired, pick up a Sheaffer calligraphy pen and use the nib unit; it will accept Sheaffer cartridges, short international cartridges, or standard converters ("ink pumps").