Repeat the first step of this tutorial on how to make boutonnieres by wiring a second pink mum. Lay the wire next to the stem and push it up thru the center of the flower head.
I generally do all similar steps at the same time. Thus, I wire all the flowers needed for a boutonniere or corsage, I then tape them all, and so forth.
Quickly bend a hook and pull it down through the head, sinking it just below the center of the flower.
Using florist tape, secure the wire firmly to the flower stem.
Bend the head gently forward and tuck this flower above the first one wired.
Flowers should be clustered tightly, with no gaps showing between the flowers unless you plan to fill in with more flowers, ribbon or other decorative accent.