YK
first_sn = models.ForeignKey(
'ServiceNote',
related_name="ServiceNote_first",
on_delete = models.CASCADE,
blank = False,
null = False,
unique = False,
verbose_name = 'Служебная записка',
)
other_sn = models.ManyToManyField(
'ServiceNote',
related_name="ServiceNote_other",
blank = True,
unique = False,
verbose_name = 'Другие Служебные записки',
)

