SSIS - Loop within an "Union All" Transformation?

I have an "Union All" transformation that inputs the following:
a. A dataset with columns 1, 2, and 3 (with several rows):

column1      column2      column3
   11            12            13
   21            22            23
   31            32            33



b. A dataset with only one column and only one row:

OnlyColumn
       5



I would like to add item b to item a. The "Union All" transformation would work, except that I need the following result:

column1      column2      column3      OnlyColumn
    11               12           13                 5
    21               22           23                 5
    31               32           33                 5

But I am getting the following result:
column1      column2      column3      OnlyColumn
    11              12           13                  5
    21              22           23               NULL
    31              32           33               NULL
 
Is there any way to make this happen?