I am having trouble tying to add a feature (reference plane) to a new folder. I am able to do it with components using "swAssy.ReorderComponents", but this method does not work with features.
You would only use IModelDocExtension::ReorderFeature if you need to add a newly created feature to an existing folder. If you need to add an already existing feature to a new folder, you can select it using IFeature::SelectX or IModelDocExtension::SelectByID2 and then use IFeatureManager::InsertFeatureTreeFolder2.
For example, this will put the last feature in a part feature tree in a new folder:
Dim swApp As SldWorks.SldWorks
Dim swModel As SldWorks.ModelDoc2
Dim swFeat As SldWorks.Feature
Dim swFeatMgr As SldWorks.FeatureManager
Set swApp = Application.SldWorks
Set swModel = swApp.ActiveDoc
Set swFeat = swModel.FeatureByPositionReverse(0)
Set swFeatMgr = swModel.FeatureManager
SolidWorks API Development Services
You should be able to simply right click any feature or reference plane and select "Add to New Folder" from the feature tree ...
I need to do it through API
Found it: 2016 SOLIDWORKS API Help - ReorderFeature Method (IModelDocExtension)
Check this out
I actually do need to add it to an existing folder now, but thanks for the clarification.
Retrieving data ...