As much as she hates him leaving the safety of the caves, Melanie can't stop Jamie from coming out with them when they go to pick Wanda a new body.
And in truth she doesn't want to.
It's a good thing he came along, in the end, because with Ian refusing to leave Doc's room she doesn't really know who she's supposed to get. Jared's no real help because he doesn't really know Wanda but even sharing the same head space doesn't seem to be helping Melanie with this.
Jamie keeps on vetoing various people that either she or Jared point out and after he explains she understands why that couldn't possibly be Wanda.
This time though she thinks she's got it.
Jamie agrees.