You can do this if it is a custom control.
In the user control, specify a new method that adds the delta part and displays it (you can use jQuery).
The new method should also add aggregation, but should not trigger re-rendering. Verify Add Aggregation Method Definition
addAggregation(sAggregationName, oObject, bSuppressInvalidate?)
the bSuppressInvalidate, true, .
:
customControl.prototype.addNewImage(img){
this.addAggregation(sAggregationName, img, false)
}
,