create a class which will inherit from checkbox

add a property: chrcontrolsource && will hold the AliasName.FieldName
&& leave controlsource blank

add the following to the different procedures
PROCEDURE Refresh
dodefault()

thiscontrolsource=this.chrControlSource
if &thiscontrolsource="Y"
this.value=1
else
this.value=0
endif
ENDPROC


PROCEDURE InteractiveChange
oldalias=alias()
local thiscontrolsource
thiscontrolsource=this.chrControlSource
if this.value=1
select (this.cchildtable)
replace &thiscontrolsource with "Y"
else
select (this.cchildtable)
replace &thiscontrolsource with "N"
endif
select (oldalias)
dodefault()
ENDPROC