diff --git a/src/mol-repr/representation.ts b/src/mol-repr/representation.ts
index a0868ba3cc0532cebc2297f733dd97af5bdd0e23..59f07b03e147652cf747b35b1a4eedfd3fbd183f 100644
--- a/src/mol-repr/representation.ts
+++ b/src/mol-repr/representation.ts
@@ -67,6 +67,7 @@ interface Representation<D, P extends RepresentationProps = {}> {
     readonly label: string
     readonly renderObjects: ReadonlyArray<RenderObject>
     readonly props: Readonly<P>
+    readonly params: Readonly<PD.Params>
     createOrUpdate: (ctx: RepresentationContext, props?: Partial<P>, themeProps?: ThemeProps, data?: D) => Task<void>
     getLoci: (pickingId: PickingId) => Loci
     mark: (loci: Loci, action: MarkerAction) => boolean
@@ -75,7 +76,7 @@ interface Representation<D, P extends RepresentationProps = {}> {
 namespace Representation {
     export type Any = Representation<any>
     export const Empty: Representation<any> = {
-        label: '', renderObjects: [], props: {},
+        label: '', renderObjects: [], props: {}, params: {},
         createOrUpdate: () => Task.constant('', undefined),
         getLoci: () => EmptyLoci,
         mark: () => false,
@@ -84,8 +85,9 @@ namespace Representation {
 
     export type Def<P extends RepresentationProps = {}> = { [k: string]: (defaultProps: P) => Representation<any, P> }
 
-    export function createMulti<D, P extends RepresentationProps = {}>(label: string, defaultProps: P, reprDefs: Def<P>): Representation<D, P> {
-        let currentProps: P = Object.assign({}, defaultProps)
+    export function createMulti<D, P extends RepresentationProps = {}>(label: string, getParams: (ctx: ThemeRegistryContext, data: D) => PD.Params, reprDefs: Def<P>): Representation<D, P> {
+        let currentParams: PD.Params
+        let currentProps: P
         let currentData: D
 
         const reprMap: { [k: number]: string } = {}
@@ -111,8 +113,16 @@ namespace Representation {
                 reprList.forEach(r => Object.assign(props, r.props))
                 return props as P
             },
+            get params() {
+                return currentParams
+            },
             createOrUpdate: (ctx: RepresentationContext, props: Partial<P> = {}, themeProps: ThemeProps = {}, data?: D) => {
                 if (data) currentData = data
+                if (data && data !== currentData) {
+                    currentParams = getParams(ctx, data)
+                    currentData = data
+                    if (!currentProps) currentProps = PD.getDefaultValues(currentParams) as P
+                }
                 const qualityProps = getQualityProps(Object.assign({}, currentProps, props), currentData)
                 Object.assign(currentProps, props, qualityProps)
 
diff --git a/src/mol-repr/structure/complex-representation.ts b/src/mol-repr/structure/complex-representation.ts
index 607a1047b87f479f60330c241132239f88548098..67cc444de839f1849f1ca1056da30870baea249d 100644
--- a/src/mol-repr/structure/complex-representation.ts
+++ b/src/mol-repr/structure/complex-representation.ts
@@ -13,17 +13,23 @@ import { ComplexVisual } from './complex-visual';
 import { PickingId } from 'mol-geo/geometry/picking';
 import { MarkerAction } from 'mol-geo/geometry/marker-data';
 import { RepresentationContext } from 'mol-repr/representation';
-import { Theme, ThemeProps, createTheme } from 'mol-theme/theme';
+import { Theme, ThemeProps, createTheme, ThemeRegistryContext } from 'mol-theme/theme';
+import { ParamDefinition as PD } from 'mol-util/param-definition';
 
-export function ComplexRepresentation<P extends StructureProps>(label: string, defaultProps: P, visualCtor: () => ComplexVisual<P>): StructureRepresentation<P> {
+export function ComplexRepresentation<P extends StructureProps>(label: string, getParams: (ctx: ThemeRegistryContext, data: Structure) => PD.Params, visualCtor: () => ComplexVisual<P>): StructureRepresentation<P> {
     let visual: ComplexVisual<P> | undefined
 
     let _structure: Structure
-    let _props: P = Object.assign({}, defaultProps)
+    let _params: PD.Params
+    let _props: P
     let _theme: Theme
 
     function createOrUpdate(ctx: RepresentationContext, props: Partial<P> = {}, themeProps: ThemeProps = {}, structure?: Structure) {
-        if (structure) _structure = structure
+        if (structure && structure !== _structure) {
+            _params = getParams(ctx, structure)
+            _structure = structure
+            if (!_props) _props = PD.getDefaultValues(_params) as P
+        }
         _props = Object.assign({}, _props, props)
         _theme = createTheme(ctx, { structure: _structure }, props, themeProps, _theme)
 
@@ -51,6 +57,7 @@ export function ComplexRepresentation<P extends StructureProps>(label: string, d
             return visual && visual.renderObject ? [ visual.renderObject ] : []
         },
         get props() { return _props },
+        get params() { return _params },
         createOrUpdate,
         getLoci,
         mark,