There is a Legacy version
here.
Fuse Stance Feat 18*Monk Source Player Core 2 pg. 126 1.1Archetype Sister of the Golden ErinysPrerequisites at least two stances
* This version of the Fuse Stance feat is intended for use with an archetype and has a different level for access than the
original feat.
You have combined two stances into a single stance all your own. When you take this feat, choose two stances you know and combine them into a single fused stance. Give your new fused stance a unique name. When you enter your fused stance, you gain all the effects of both stances, including the requirements and restrictions.
If the stances both grant special attacks, you gain all those attacks. If a stance restricts you to one particular attack (such as
Crane Stance), you must abide by that restriction. If the fused stances have incompatible restrictions, the GM determines which apply, or determines you can't fuse those stances at all.
Archetype Use
This feat can be used for one or more archetypes in addition to the listed classes. When selected this way, the feat does not have its class traits.