Sub podosnova_test()
Dim oCompDef As AssemblyComponentDefinition
Set oCompDef = ThisApplication.ActiveDocument.ComponentDefinition
Dim occP1 As ComponentOccurrence: Dim occP2 As ComponentOccurrence
Set occP1 = oCompDef.Occurrences.ItemByName("Part1")
Set occP2 = oCompDef.Occurrences.ItemByName("Sub").Definition.Occurrences.ItemByName("Part2")
Dim eF As ExtrudeFeature: Set eF = oCompDef.Features.ExtrudeFeatures(1)
Call eF.AddParticipant(occP1)
'Call eF.RemoveParticipant(occP1) 'ошибка, если подосновы нет в выдавливании
'Call eF.AddParticipant(occP2) ' не работает :(
End Sub