User form opens twise

I have 2 excel files.

1-Master which contains the UserForm1
2-Slave which has some codes.

The form opens the slave, then hides the form ("me.hide") to allow working with the slave.
After the slave file is been done working with, I activate a procedure in the Slave which should call the Master, unhide the UserForm and update some fields:

[code]RUN "Master.xls!ShowUF(field1,field2)"[\code]

In the Master I have the ShowUF macro who looks like this:
[code]
Sub ShowUF1(field1 As String, field2 As String)
UserForm1.Label1 = field1
UserForm1.Label2 = field2
UserForm1.Show
End Sub
[\code]
Everything works fine except it opens in the background another instance of the UserForm with only label1 and label2 "populated" controls.

Tricked it

I finally chose to trick it.
Instead of Hide/Show
I just open the userform as [modal] = false and moved it out of the screen when I don't use it (instead of me.hide), and move it back to the center of the screen when I need it (instead of Show).

It would be much simpler to

It would be much simpler to have all the code in this instance run from within the master.. You could end the routine with me.show and the original userform will reappear.

not in this particular case

Not in this case. The procedure in the slave is coplex and involves "SelectionChange" event which can't be coded in the Master.
In this particular case I need to call the "Show" from outside the UserForm, which is giving me the headake, because it opens the userform twise.
Or at least maybe I can run a sub located in the Userform? How would I address that?