Why do property changes in child controls get copied to the parent control?

[lisa]

I have a control that contains a collection of another control. When I
make a change in a property of one of the members of the collection
(using the collection editor), the new property values appear correctly
on the collection member, but they also appear on the parent control.

Since the parent control and the controls in the collection have some
properties with the same name, this presents a problem.

Is there something I need to change in the property definitions of the
child controls? An attribute, maybe?

TIA,
Lisa