Your "Sikh" cousins would never qualify for Sikh regiment. Yes, I know there are sardars (who don't grow full beards and trim) and clean cut Sikhs in other regiments, but the real regiment, which has the Khalsas, the REAL Sikhs, is the Sikh regiment, and its numbers were limited by Indian government. In Sikh regiment, you are not allowed to cut even inch of hair, you are not allowed to bring alcohol or any drugs on the base, you must stricly adhere to the Rehat Maryada, the Sikh code of conduct. It is a deeply religious regiment. Infact, when Operation Bluestar happened, many soldiers of Sikh regiment at the HQs at Ramgarh in Bihar mutinied, killed their commander, General RS Puri, and started heading to Punjab with truckloads of weapons as they thought they had been betrayed by Indian army. Another Sikh unit deployed down south in Pune also rebelled. This led to the Indian army mixing many of the originally purely battalions into mixed Hindu-Sikh battalions (called Vaidya's Battalions, because General Vaidya came up with idea of diluting the Sikh regiments). Although, Sikhs managed to maintain their regiment, 13th Sikhs, still ended up being mixed and is called a "Vaidya Battalion". So I don't know if you guys are misinformed about Sikh regiment or what, but that is only a small insight.
As for RSS, attacking Sikh religion, its very much a reality:
Rashtri Sikh Sangat RSS Hinduization