Change To:-header when replying

[Til Schubbe <t.schubbe@xxxxxx>]

Hi,

how can I change the To:-header when replying to a certain person
(included overriding his Reply-To:)?

Someone has 3 mail-addresses, lets say:
1. realname@xxxxxxxxxxx
2. 970898709@xxxxxxxxxxxxxx
3. rgihugrvg@xxxxxxxxxxxxxx

His header mostly looks like this:
From: 970898709@xxxxxxxxxxxxxx
Reply-To: rgihugrvg@xxxxxxxxxxxxxx

I want mutt to put
To: realname@xxxxxxxxxxx
in my reply.

How can I do this?

I tried this, but it doesn't work:

reply-hook '~t 970898709@xxxxxxxxxxxxxx | ~t rgihugrvg@xxxxxxxxxxxxxx' \
        "my_hdr To: realname@xxxxxxxxxxx"

I have
set autoedit=no
so mutt asks me for the To:-header, but I want to override/change
the Reply-To: mutt suggests automatically.

TIA
Til