https://github.com/Yakindu/sctpro/issues/1453

for every declaration a new DerivedEList was created. Use direct access
to members instead of declarations

plugins/org.yakindu.sct.model.sexec/src/org/yakindu/sct/model/sexec/transformation/StructureMapping.xtend

@@ -97,7 +97,7 @@ class StructureMapping {
 	}
 	
 	protected def doCreateAndAddImportDecl(Declaration decl, Scope scope){
-		scope.declarations += SGraphFactory.eINSTANCE.createImportDeclaration => [
+		scope.members += SGraphFactory.eINSTANCE.createImportDeclaration => [
 			name = decl.name
 			declaration = decl
 		]