Can An Onchange Eventhandler Be Re-used By Invoking Rather Than Clicking?

I'm trying to call/ mimic an onchange function/ event after a user has
clicked a checkbox. In response to which a buncch of other ones need to be
checked as well.

The caveat is that each of those child-checkboxes need to have an onchange
action take place. All of these child-boxes *have* got a working onchange
eventListener attached (thx to an old post of Lasse Reichstein Nielsen).

Following a snip that suggests (or so the debugger suggests) that the
inputElement.onchange is void, so calling onchange becomes a bit hard.
Any suggestions?

.....
inputElement = _row2checkbox[tb.rows[i]["id"]];
inputElement["checked"] = el["checked"];
if (inputElement.onchange) {
inputElement.onchange();
}
.....

I did come up with a work-around but that ivolves some serious trickery.