camorrow
He's a cutie! I really like his colour.
Regarding introducing new birds....
It is usually recommended to quarantine new birds for a period of time, to make sure that you don't introduce any disease to your home birds.
After this period of quarantine, it's advised to place the new bird in a cage close to your other birds, so that they can see each other and get to know one another. Then it's advised that you remove both birds, and change things around in the main cage, like moving the perches and food dishes and decorations around a bit. It's only after that process that you place them in a cage together.
That said, it now would be like closing the barn door after the horses have escaped, lol.
Seeing that they are already together, I would keep a close eye, to see that they are getting along. Zebras, both male and female are territorial by nature, and don't like intruders in their space.
I would make certain, that you have two seed and two water dishes at opposite sides of the cage. Also two high perches for sleeping, so that they don't have to fight over them.
I would also add some new greenery, maybe a new swing etc.
Good luck.