capture template for interval

[David Belohrad <david@belohrad.ch>]

Dear All,

with a help of this mailinglist I have setup my capture template for
appointments as follows:

(setq org-capture-templates
        '(
	        ("a" "Appointment (compulsory)" entry (file+datetree (concat my-org-files "diary.org"))
           "* %? :appt:\n%a\n%^T\n\nEntered on %U")
          ))


This makes appointment in the diary.org file, it puts there a link to
the actually visited file (notmuch buffer mostly) and then asks for a
date+time.

Now this appears in my agenda, but only as as a simple date. Now I'd
like to get it done in a way that I enter one date time, and another one
is 'offered' to me in 2 hours in the future from the date I have given
as first.

So basically if I do not put the second date, it will by default create
an interval long 2 hours. 

any possibility how to do this?

many thanks
..d