Sissies all need breasts whether they want them or not. He’ll feel unnatural about the attention they’ll receive at first, but he must learn to accept his new charms. It won’t be too long before he’s complaining about how small they are compared to yours!
Tip: Have him experiment with different types of bras and insist he sleep in one for the first six months to grow accustom to his new necessity. When he asks permission to wear a push-up bra, you can be assured he is ‘coming along’ nicely!