How do I get multiple mc to come to the front on focus

Question

I know it has something to do with swapDepths and/or
getNextHighestDepth. I have tried both extensively for almost 2
weeks. No success! I know I'm doing something wrong.
I have a base movie clip (a Yahoo map using Flash API) that
loads 18 separate clips (customSWFMarkers).
Each of the 18 separately loaded clips is a button which,
onRollOver, goes to Frame 2 and attaches new movie clip. The new
movie clip contains a dynamic text field.
This base movie clip works fine except onRollOver some of the
18 separate mc overlap others. I need each one to appear on the top
layer onRollOver.
IMHO, the problem lies with the 18 separate loaded clips.
Here is a sample of the movie clip in action. In this
example, I have loaded only 5 of the 18 clips; the others have been
commented out so they don't appear. Notice that markers 1 & 2
and markers 3 & 4 should each move to the top on focus; but,
they do not:
http://www.fairfieldpromoswest.net/flash/
Code in the loaded clip:
On Frame 1:
marker_btn.onRollOver = function() {
_parent.x +=2;
_parent.marker_btn.swapDepths(_root.x);
gotoAndStop(2);
marker_mc.attachMovie ("details","propertyCasaSF",50)
stop();
n.b. the instance name "propertyCasaSF" is different in each
loaded clip
On Frame 2:
marker_mc.onRollOut = function() {
marker_mc.unloadMovie();
gotoAndStop(1);
marker_mc.onRelease = function() {
getURL("
http://www.mydomain.com",
target="_blank");
gotoAndStop(1);
stop();
On Frame 1 of attached MC (i.e. "details" linked from
library):
init();
function init() {
descrip2.htmlText = "<snipped lenghty text>";
descrip2.backgroundColor = 0xcccc99;
descrip2.borderColor = 0x003366;
descrip2.embedFonts = True;
stop();

Answer 1

Originally, I had _root instead of _parent; it wasn't working
then either. I changed it because I thought it was seeing the base
map MC as the root and not the MC that attaches a new MC (if that
makes any sense at all).
My thinking is that the base map MC is the parent of all of
the 18 MCs. So that should be okay, right?