jm l+m"áAÓ<£ÑÒ]®_½|mìP«V=¶÷õL¯I might be more confused about this than you, but my understanding is that the basic approach is to do a transfer that only works in one chain (a faucet might help with this).
https://whatsonchain.com/tx/3df5a2e7ae24d1adf07de96d5a668e6d2067ae61eb1c9f2d7c2738fa0fd79738