How can I modify a row in a function such that the caller sees it?

Bit of a nooby Q, tho I have researched this quite a bit and found nothing
and it seems simple: I just want to modify a row in a plpgsql function such
that the change can be seen by the caller.

The functions happen to be called in a before trigger, to finish
initializing the row. The functions are named in a column of the new row,
so they are effectively callbacks.

The closest I have come was an error saying the function returned nine
columns, which is great because the row has nine columns. :)

Somewhat condensed (I know, I know <g>) Here is the calling trigger
function:

CREATE OR REPLACE FUNCTION dcm.biz_proc_init()
RETURNS trigger AS
$BODY$

declare
bpnew dcm.biz_proc;
begin
if NEW.timing_initializer is not null then
execute 'select ' || NEW.timing_initializer || '($1)'
using NEW
into bpnew;
return bpnew;
else
return NEW;
end if;
end;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;

Here is a callback:

CREATE OR REPLACE FUNCTION dcm.test_bp_init(bp dcm.biz_proc)
RETURNS dcm.biz_proc AS
$BODY$

declare
begin
bp.max_duration_time = now() + interval '30 days';
return bp;
end;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;

If the above looks OK I will carve out an actual disclosable pile of SQL to
recreate the problem, but this seems like a trivial thing so I am hoping I
just have missed the right bit of documentation of something
straightforward.

-ken