Looking for Code to Expand Subform Rows Automatically

I've created a form that contains five levels of subforms - each a subform
of 
the parent above it.  Each subform is displayed as a datasheet.
Form
  Subform1
    Subform2
      Subform3
        Subform4

Normally, the user selects a key from a combo box on Form that filters the

recordset of Form to a particular record.  Access populates the Subforms 
based on parent/child relation****ps between the tables used as data
sources 
for the Subforms.  I then leave it up to the user to navigate through the 
subform rows by manually expanding and/or contracting the various row 
indicators. 

Now I've found a case where I would like to have Access automatically
expand 
the necessary subform rows to display a particular row on Subform3.  The
user 
will supply the key data to identify the row to be pointed to on Subform3
by 
using another combo box on Form.  A query will provide the key data
necessary 
to identify the applicable Form record and Subform1 and 2 rows.

So, with all the key data available, I’m looking for the code to cause 
Access to expand the necessary rows and focus on the Subform3 row
selected.