i think this should still be possible, the problem with this example is that the start & end are missing
for instance (these are fictive dates):
original member: Ian McDonald (background vocals) (1990 - 1991)
original member: Ian McDonald (background vocals, flute) (1994 - 1995)
original member: Ian McDonald (flute) (1997 - 1999)
original member: Ian McDonald (flute, saxophone, mellotron, keyboard) (2001 - 2005)
but if you split them all up it would look like this:
original member: Ian McDonald (background vocals) (1990 - 1991)
original member: Ian McDonald (background vocals) (1994 - 1995)
original member: Ian McDonald (flute) (1994 - 1995)
original member: Ian McDonald (flute) (1997 - 1999)
original member: Ian McDonald (flute) (2001 - 2005)
original member: Ian McDonald (saxophone) (2001 - 2005)
original member: Ian McDonald (mellotron) (2001 - 2005)
original member: Ian McDonald (keyboard) (2001 - 2005)
wich makes the list much longer then neccessairy.
i do understand that if the band doesn’t split up and reform again but they just switch functions it could be cleaner:
original member: Ian McDonald (background vocals) (1990 - 1995)
original member: Ian McDonald (flute) (1994 - 2005)
original member: Ian McDonald (saxophone) (2001 - 2005)
original member: Ian McDonald (mellotron) (2001 - 2005)
original member: Ian McDonald (keyboard) (2001 - 2005)
but i don’t think this happes very often, mostly people play a (or multiple) instrument(s) and when they quit the band and rejoin, they play the same set of instruments.
so i think it is important that the start & end date are taken into account