ihack,
you've been given some very good options on how to accomplish this task, and yet you ask for more.
1. Route it to a huntgroup with an overflow containing another user
OR
2. Put a USER button on another users phone with the receptionist as action data. That button will light up when a call comes in.
OR
3. But a bridged or coverage appearance button on the other users phone tied to the receptionist
OR
4. Put a GROUP button on another users phone so they can see calls in the group and pick them up.
OR
5. Put both users in the main group, ring them sequentially, give the receptionist a DND button. When she is not available it'll ring to the other user.
OR
6. Put a NIGHT/LUNCH button on the receptionist phone, that sets her group to fallback, which rings another group with the user you need in it.
You want step by step details. Don't we all. Luckily the manager program is easy as heck to use.
I don't want to come off as rude, but you really should do yourself a favor and take some courses and read documentation. The HELP button in manager is very useful too. This forum really is meant for problems encountered by systems engineers and technicians, not general inquiries on how to do very basic administration. We've all spent countless hours and dollars/euros/yen/caps/septims learning this stuff.
I know the adage, teach a man to fish, feed him for a lifetime; but you have to at least know that water is wet first.
-Austin
ACE: Implement IP Office