Chris Brown -- Baby Mama's BF ... Step Aside Breezy, I'll Parent Royalty

The boyfriend of Chris Brown's baby mama is hitting Chris where it hurts most ... fatherhood.

King Ba dumped Nia Guzman after he learned her 9-month-old baby was fathered by Brown. But we've learned they're back together, and Ba is treating Royalty like his own.

He's posted pics of the two of them, saying, "Been a Dad Still a Dad... Minus All the Nonsense That Been Going On We Still Kick It." He seems to be saying he acted like Royalty's dad before he learned Chris was the biological father, and now he's over technicalities and is stepping in as a parent.

Ba and Nia had an Easter celebration with Royalty and her older kid, so it looks like Ba is backing up his intentions with actions.

As for Chris ... he's far, far away in Africa.