Passing vars between 2 seperate .swf files?

[COLOR=#003366]Basically…i have two .fla files.[/COLOR]

[COLOR=#003366]- in the parent.fla i created a dynamic txt box and var String named ‘txt’,[/COLOR]
[COLOR=#003366]this initialises the dynamic text box content to say “parent value”. [/COLOR]

[COLOR=#003366]- in the child.fla i tried to assign and send a [/COLOR]
[COLOR=#003366]new string value i.e. “child value” to ‘var txt’ which in found [/COLOR]
[COLOR=#003366]within parent.fla. [/COLOR]
[COLOR=#003366]At this point if everything was [/COLOR][COLOR=#003366]to work fine the dynamic txt box in parent.fla should output “child value”.[/COLOR]

[COLOR=#003366][/COLOR]
[COLOR=#003366]Could sombody please show me the best way to achieve this.[/COLOR]