I know my sample is useless. but if you don't want to eat up stack, you have
to exit a sub first, and then have to call another sub. i think your code is
something like this and this will eat up your stack.

Sub func1()
   func2
End Sub

Sub func2()
   func3
End Sub

Sub func3()
   func1
End Sub

Though this is a one way, but with a public variable in standard module and
by manipulateing it from userform, I think you could control the sequences
of your forms coming up. this may be another useless sample. CommandButton2
is a "back" button, though it could back only one step.
run showform, though this is endless sub.

in standard module
Type fstate
   nstate As Long
   pstate As Long
End Type

Public fs As fstate

Sub showform()
fs.nstate = 1
fs.pstate = 1
Do
   If fs.nstate = 1 Then
       UserForm1.Show
   ElseIf fs.nstate = 2 Then
       UserForm2.Show
   ElseIf fs.nstate = 3 Then
       UserForm3.Show
   Else
       Exit Do
   End If
Loop
End Sub

in UserForm1 module
Private Sub CommandButton1_Click()
Me.Hide
fs.nstate = 2
fs.pstate = 1
End Sub

Private Sub CommandButton2_Click()
Me.Hide
fs.nstate = fs.pstate
End Sub

in UserForm2 module
Private Sub CommandButton1_Click()
Me.Hide
fs.nstate = 3
fs.pstate = 2
End Sub

Private Sub CommandButton2_Click()
Me.Hide
fs.nstate = fs.pstate
End Sub

in UseFform3 module
Private Sub CommandButton1_Click()
Me.Hide
fs.nstate = 1
fs.pstate = 3
End Sub

Private Sub CommandButton2_Click()
Me.Hide
fs.nstate = fs.pstate
End Sub

keizi