Chris Brown And Baby Mama Throwing $30k 4th Birthday Party For Royalty

Chris Brown and his baby mama, Nia Guzman, have called a truce in their never-ending custody war ... deciding for the sake of Royalty that they'll throw a joint 4th birthday party.

Royalty turns 4 on Sunday and we're told there's only gonna be one bash this year. In the past, Chris and Nia have each thrown their own parties for Royalty because they weren't speaking to one another, but we're told they're actually on good terms now ... trying to co-parent.

Royalty wanted a princess ball for her birthday and Chris and Nia are planning to go all out by dropping well north of $30k on the party. We're told every Disney princess from Cinderella to Jasmine will be there along with a fairy godmother. They're having a horse and carriage with a grand duke and coachman.

On the menu ... crab cakes, California rolls, shrimp tempura, as well as peanut butter and jelly sandwiches, mac and cheese and burgers for the kids.