Add extra column in insert with instead of trigger - sql

Question

EDIT 1:Basically I want to do
INSERT INTO Users(col1, col2, col3) when Users only have col1 and col2 , col3 doesn't exist.
I have a table UsersAddresses with two int fields "User" and "Addresses" which that binds my table Users to another table Addresses. I need to audit any change made to my user so I have a trigger on my Users that works fine, any changes made to my Users table creates a line in the audit table.
The problem is that I also need to trigger the same trigger if I add an addresses to my user. So I create a trigger on my UsersAddresses that will do an update of the Users table. But I need to have the modifierId aswell (to know who wanted to make this change) So I figure out I should alter the way I insert in UsersAddresses to add this Id. I've tried the following, adding a fake "ModifierId" but as expected I get "invalid column name" when I try to add this trigger.
Do you know what I should do ?
Thankfully
CREATE TRIGGER UpdateUser
ON [dbo].[UsersAddresses]
INSTEAD OF INSERT
AS
DECLARE #User INT;
DECLARE #Address INT;
DECLARE #ModifierId INT;
SELECT #User = [User] FROM inserted;
SELECT #Address = [Address] FROM inserted;
SELECT #ModifierId = [ModifierId] FROM inserted;
INSERT INTO [UsersAddresses]([User], [Address])
VALUES (#User, #Address);
UPDATE [Users]
SET [CreatorId] = #ModifierId
WHERE [Id] = #User;
Edit Solution: Credits to Michael
use context_info with a procedure.:
CREATE TABLE [dbo].[UsersAddresses] (
[User] INT NOT NULL,
[Address] INT NOT NULL,
CONSTRAINT [PK_UsersAddresses] PRIMARY KEY CLUSTERED ([User] ASC, [Address] ASC),
CONSTRAINT [FK_ToUser] FOREIGN KEY ([User]) REFERENCES [dbo].[Users] ([Id]),
CONSTRAINT [FK_ToAddress] FOREIGN KEY ([Address]) REFERENCES [dbo].[Addresses] ([Id])
);
GO
CREATE TRIGGER [ChangeToUsersAddresses]
ON [dbo].[UsersAddresses]
FOR DELETE, INSERT, UPDATE
AS
BEGIN
IF ( (SELECT COUNT(*) FROM inserted) > 1)
THROW 51000, 'To many records', 1
DECLARE #UserId INT;
IF (SELECT [User] FROM inserted) IS NOT NULL
SELECT #UserId = [User] FROM inserted
ELSE
SELECT #UserId = [User] FROM deleted
INSERT INTO [Audit_Users](UserId,ActiveDirectory,FirstName,LastName,Type,Status,ModifierId,Date)
SELECT [Id], [ActiveDirectory], [FirstName], [LastName], [Type], [Status], [dbo].GetUserContext(), GETDATE()
FROM [dbo].[Users] WHERE [Id] = #UserId
INSERT INTO [Audit_UsersAddresses]([User], [Address])
SELECT ##IDENTITY, [Address]
FROM [UsersAddresses]
WHERE [User] = #UserId;
END;
GetUserContext() that is used in the insert :
CREATE FUNCTION [dbo].[GetUserContext] ()
RETURNS INT
AS
BEGIN
RETURN COALESCE(CONVERT(INT, CONTEXT_INFO()), 0)
END
And Finally the procedure to set the context.
CREATE PROCEDURE [dbo].[SetUserContext]
#userId INT
AS
BEGIN
SET NOCOUNT ON;
DECLARE #context VARBINARY(128)
SET #context = CONVERT(BINARY(128), #userId)
SET CONTEXT_INFO #context
END