Span barlines on different sized staves

[Leo Correia de Verdier]

I have the following situation:

\version "2.20.0"
\new StaffGroup
<< \new Staff \with { \magnifyStaff #2/3 }
   {c''1 \bar "|."}
   \new Staff
   {c'1 \bar "|.”} >>

Where the bars on the different sized staves have different thicknesses 
according to their staff size. How would be the best way to get them all to the 
thickness of bar on the larger staff and aligned?

Thanks a lot!
/Leo