Those of us with common sense and manners need to take a stand.
Decline invitations to these gift grabby events.
When no one (or only a couple people) show up for these things, THEN they will stop. And the mom can whine all she wants about how she got rid of her stuff, the baby is a different sex, or she has a different baby daddy, or the kids are X years apart, and it won't matter. Because no one is attending the gift grab and she is SOL.
Then and only then will common sense and good manners prevail.