Display a control in the last record of a continuous subform?

Hi all

A quick question which I've not been able to solve from trawling the
web.

Is it possible to have a control in the detail section of a form set
to a default view of "Continuous" which only appears on the last
record?

I'm thinking of having a form with a subform, and would like the
subform to list related records, but have a "+" button to allow adding
a new record. I know I could put it in the form footer, but that can
be quite a way away from the data, if there are only one or two
records showing, so I wondered if there's a way of controlling the
visible property with (presumably) some reference to the current
record's position within the recordset. And which event would need to
trigger this code?

Thanks in advance.

Regards
Andrew