How To Make The New Column Available To Upate?

I have a store procedure to create a table temp, populate data from Origin1 table, and then add a new column SSN to temp table, update the SSNs from another table. but the following code gives error, pleaes help!

Create table temp (
....
)
Insert into temp
select * from Origin1

Alter table temp ADD Name int

Update temp
Set SSN = (select SSN from Origin2
where id = Origin.id)

it gives 'Invalid column name: 'SSN'
I am aware that the add new column doesn't take effect until end of the SP, but there must be a way, Thanks for any inputs.