Checkear CheckBoxes Dependientes

[TurKa]

Que tal Kan?
Fíjate si este código que te hice de ejemplo, te viene bien:

Código HTML:

<SCRIPT LANGUAJE="javascript">
function tildar(form) {
if(form.autos.checked == true) {
	form.chevrolet.checked = true;
	form.dodge.checked = true;
	form.torino.checked = true;
	}
else {
	form.chevrolet.checked = false;
	form.dodge.checked = false;
	form.torino.checked = false;
	}
if(form.otros.checked == true) {
	form.otros1.checked = true;
	form.otros2.checked = true;
	form.otros3.checked = true;
	}
else {
	form.otros1.checked = false;
	form.otros2.checked = false;
	form.otros3.checked = false;
	}
}
</script>
<FORM NAME=formulario>
<INPUT TYPE=CHECKBOX NAME=autos onClick="tildar(this.form)" VALUE="ON"> AUTOS<BR>
---> <INPUT TYPE=CHECKBOX NAME=chevrolet VALUE="ON"> Chevrolet<BR>
---> <INPUT TYPE=CHECKBOX NAME=dodge VALUE="ON"> Dodge<BR>
---> <INPUT TYPE=CHECKBOX NAME=torino VALUE="ON"> Torino<BR>
<BR>
<INPUT TYPE=CHECKBOX NAME=otros onClick="tildar(this.form)" VALUE="ON"> OTROS<BR>
---> <INPUT TYPE=CHECKBOX NAME=otros1 VALUE="ON"> Otros 1<BR>
---> <INPUT TYPE=CHECKBOX NAME=otros2 VALUE="ON"> Otros 2<BR>
---> <INPUT TYPE=CHECKBOX NAME=otros3 VALUE="ON"> Otros 3<BR>
</FORM> 

Saludos!