There must be a way to store fiat currency in multisig addresses so signers can control the release of the fund, in order for BCE to work.
The signers, like in any escrow, has to keep the fiat fund before releasing, not just the payment token (e.g. Perfect Money e-Voucher numbers), to prevent double spending.
I guess using APIs of fiat e-wallets (e.g. Perfect Money ) it could be done.
Interesting thougts.