[bombcar]

Now I'm wondering if it is a "legal" chess position to get the pieces to swap sides ... a solver to find how to do it would be amusing.

[mlyle]

Obviously not possible -- how would pawns pass each other without captures?

[bombcar]

Ah! True, I worked out how you could have OTHER pieces get around a pawn, but pawns themselves can't get past each other.

[NitpickLawyer]

Not what you asked for, sorry, but it reminded me of this gem - https://www.youtube.com/watch?v=C5JVFCouXIU