Hi Chistropher

Is there a table where all the possible proccesses are stored.
So you may have
acquire permit
remove old roof
remove gutters
apply underlayment
apply shingles
install seamless aluminum gutters and downspouts
final building inspection

plus (maybe)
return to inspect work after 4 weeks
or
pre-site survey
etc
etc

Just a thought

Presumably you have one table for the invoice header (shown on the main
form), and a related table for the invoice line items (shown in the
subform.) The related table will have fields like this:
   InvoiceDetailID    AutoNumber    primary key
   InvoiceID            Number           which invoice this line belongs
to.
   Quantity             Number
   Item                               probably relates to Product.ProductID
   PriceEach           Currency

If you want to define the order of the items, you need to add another field
to the InvoiceDetail table, e.g.:
   SortOrder           Number
The user can then enter whatever number they want, and you sort the items on
your invoice report by this field.

You don't have to make the SortOrder field uniquely indexed. Allowing
duplicates makes it easy to swap values. For example, if you want to swap
row 2 and 3, and they are uniquely indexed, you would need to change to 2 to
(say) 999, so you can change the 3 to 2 and then the 999 to 3. Similarly,
the numbers don't have to be sequential: they just sort in order.

The final piece of the puzzle is to automatically offer the next available
number at the point when the user starts entering a new row on the invoice.
Use the subform's BeforeInsert event procedure. Something like this (aircode
that needs changing to match your table and field names):

Private Sub Form_BeforeInsert(Cancel As Integer)
   With Me.Parent
       If .NewRecord Then
           Cancel = True
           MsgBox "Enter the invoice header in the main form first."
       Else
           Me.SortOrder = Nz(DMax("SortOrder", "InvoiceDetail", _
               "InvoiceID = " & !InvoiceID), 0) + 1
       End If
   End With
End Sub