Hinduism and others dharmic religion

Buddhists, Jains, and Sikhs often claim that their religions have no connection to Hinduism—not even a common origin or the status of a sister religion. Some even accuse Hinduism of being a copy-paste of their traditions. So, as Hindus, should we simply stop saying they are part of Hinduism or brothers ? We know that Buddha, Rishabhanath, and Guru Nanak were born into Hindu families before rejecting Hinduism and founding their own religions. Buddha and Thirthankaras and Sikhs Guru even they denies of Brahman existence, recognise existence of ours gods (incarnations of Brahman) and respected them. Our only true brother are Buddhists or Jains who pray and respect ours Hindus gods.