Udasis are Udasis, Nihangs are Nihangs, Sevapanthis are Seva panthis, Nirmalas are Nirmalas (these previous four have a very similar belief system. Belief systems start to vary amongst the following) Namdharis are Namdharis, Nirankaris are Nirankaris, Nanaksariahs are Nanaksariahs, Radha Swamis are Radha Swamis, Singh-Sabhaists are Singh-Sabhaists
Great. All of them claim to be Sikhs. All of them hold Sri Guru Granth Sahib Ji (and 10 Gurus) as their Guru. Thus it is a no-brainer to call them Sikh and to let them define who they are, without imposing our prejudiced judgements on them. The only discussion here is how they differ in their interpretation.
BTW Ahmadiyas don't claim to be Sikh, they claim to be Muslim. But a few Muslims, like our fellow Judges of Dharma here, don't accept them as Muslim, even though Ahmaddiyas have taken the Quran, Hadith and Muhammad to be their scripture and Prophet, they also practice all the rituals and festivities.
Baba Sri Chand ji, whether he was a Guru or not does not matter when we consider his importance in Sikh history. Sri Chand ji was the one who suggested that the town of Ramdaspur be called Amritsar. Guru Ramdas ji held him in high esteem and presented him with offerings of horses and money every now and then. When asked by Sri Chand ji the reasons as to why his beard is so long, he replied "to wipe off the dust of the saints like yourself". Guru ji then got down and wiped his feet.
How did Nihangs and others escape persecution to recover their ranks? They hid in jungles.
How did Udasis escape persecution? They hid in jungles and didn't wear turbans. Where do Udasis normally live and how do they normally dress since the time of Guru Nanak? In jungles and without turbans.
Why did Nihangs attain martyrdom? Well they were warriors and very much involved in politics and society and thus were more likely to be in situations where they would be martyred.
Why don't we hear about Udasis attaining martyrdom? Well they are recluses who live in deep jungles and mountains, very much outside of politics and society and thus are less likely to come under fire from the government.
Udasis and especially Nirmalas devote their entire lives to studying Sri Guru Granth Sahib Ji, so we really are in no position to judge whether they are Sikhs. They are the experts and are devoted to what they do. They understand the Sikh scriptures better and it is because of their loyalty towards the Gurus that they study it so nothing good will come from antagonizing them. Instead their texts should be studied with the same level of love and devotion that they wrote them with.
