Be aware that many people with DSDs may be entirely unaware that other people class them as 'intersex' or as a DSD at all.
For example, women and girls with Turner's syndrome would not necessarily have any reason at all to consider themselves any kind of a common group with men and boys who have Kleinfelters.
I know if a woman in her forties who has attended a lifetime of medical appointments for her Turner's syndrome, and had never once heard the term 'intersex' used in relation to her.
Those conditions and organisations that do ally themselves with other unrelated conditions under an 'intersex' umbrella, are more likely to have an agenda or advantage from such an alliance.