Tyga and Blac Chyna are on the same page after wrapping up their nasty custody battle — and will make anyone pay (literally) if they cross their son, King. According to documents obtained by RadarOnline.com, the exes agreed to get their 11-year-old baptized, but anyone who wants to watch the milestone must sign a non-disclosure agreement (also known as an NDA) and pay a hefty $500k fee if they violate it. We have a copy of the NDA, stating that Tyga and Blac Chyna — who now goes by her legal name,Angela White — request that “any and all guests or third parties in attendance also sign the Non-D…