If you are using a Pre-Approval form prior to creating your tender packages, you now have the ability to restrict how additional bidders can be added to those packages.
We added a new setting under Configure > Modules > Tenders, Package Config Step, Under Pre-Approval Form, called "Can only add new bidders from approved pre-approval form."
When this tickbox is ticked, it will restrict adding new bidders to a package to only those on the linked pre-approval form, when the form is in a Closed (not Draft or Withdrawn) status.