Golly it would be nice to add call forking instead of just call forwarding. My building uses the landline number for the door and it would be great if anybody in my family can get the call to buzz in the delivery man.
Get a Google Voice number and configure it to call all the numbers, then give that number to your building management and ask to have that programmed into the door entry system.
Why can't all members of the family just answer the household's landline?