This is one that a lot of people have asked for Microsoft Dynamics GP 2015 R2 Feature of the Day: Payables Transaction Worklow
Microsoft Dynamics GP 2015 R2 Feature of the Day: Payables Transaction Worklow – Microsoft Dynamics GP Community
Tips & Hidden FeaturesPayables & ReceivablesGP 2015
Archived post from 2015. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.