Baba Sri Chand was the elder son of Guru Nanak Dev Ji. He did not inherit the guruship and founded the Udasi order, an ascetic tradition that took celibacy and renunciation as its practice, which is precisely what his father had refused.
The Udasis nonetheless became the custodians of Sikh shrines through the eighteenth century. When the Khalsa was proscribed and its members were living in the jungles with a price on their heads, Udasi mahants held the gurdwaras, including Nankana Sahib and Harmandir at various points, because as ascetics they were not being hunted.
That custody became the problem of the twentieth century. By 1900 the mahants held the shrines as private property, with the revenues, and in a number of cases their conduct was indefensible. The Gurdwara Reform Movement of 1920 to 1925 was fought to get the shrines back, and the massacre at Nankana Sahib in 1921 was its worst episode.
Baba Sri Chand lived to about 135 by tradition and is said to have blessed Baba Gurditta Ji, son of Guru Hargobind Sahib Ji, as head of the Udasis. Dera Baba Sri Chand at Barath near Pathankot is the principal seat.
The order preserved the shrines for two hundred years and then had to be removed from them. Both halves of that are true.
The Udasi establishments accumulated manuscripts, paintings and land over two centuries, and a good deal of what survives of eighteenth century Sikh material culture survives because an akhara kept it.
The order became the custodian of Sikh shrines through the eighteenth century, when it was unsafe for Khalsa Sikhs to hold them openly, and it kept them until the reform movement of the 1920s.
He lived a very long time and is recorded as having met several of the later Gurus. The relationship between the two lines is one of the least resolved things in the tradition's own account of itself.