Confusion on aggravation and more

How does aggravating bleeding work with multiple stacks of bleeding? What if you aggravate a 100 dps bleed and then inflict a non-aggravated 200 dps bleed? Crimson Dance???
Being aggravated is a property of each individual bleeding debuff.
Stats that grant a chance to aggravate bleeding aggravate all bleeding on the target at once if they trigger (other than the one that aggravates bleeding older than 4 seconds). They do not roll their chance individually for each bleed.
The extra damage from aggravated bleeding is separate to bleeding's normal damage. This means that if you aggravate a 100 dps bleed on a target, that target is now taking 100 normal bleeding dps and 200 aggravated bleeding dps as long as it's stationary. If you then inflict a 200 dps normal bleed, that will take precedence over the normal damage from the smaller bleed, but the aggravated damage from that bleed will keep applying as long as it's the highest aggravated bleed damage and the monster is stationary. The target would be taking 400 dps when stationary, or 600 while moving.
Aggravating a bleed has no effect with Crimson Dance, as there is no extra damage to deal.
If you aggravate bleeding on hit, and inflict a bleed with that same hit, the new bleed will not be aggravated. You'd have to hit again to aggravate it. The Gladiator's Jagged Technique passive is the only way to apply an aggravated bleed in a single hit.