If it helps, here is some code that came from one of my DB's. What I opt to do is open another form in Data Entry mode. I set the Data Entry mode in the other form's properties and save it. Also, the other form is pop up/modal.
Code:
Response = acDataErrContinue
Dim intMsg As Integer
intMsg = MsgBox("That Species does not exist within the list." & vbCrLf & _
"Do you want to add a new species?", vbYesNo + vbQuestion + vbDefaultButton2, "Item Not Found")
If intMsg = vbYes Then
Me.cmbSpecies.Value = ""
If Me.Dirty Then Me.Dirty = False
DoCmd.OpenForm "frmSpeciesEntry"
Else
Me.cmbSpecies.Value = ""
End If