See the protocol diagram here: https://bitcointalk.org/index.php?topic=321228 https://bitcointalk.org/index.php?topic=321228 (alice and bob can be played by th

See the protocol diagram here: https://bitcointalk.org/index.php?topic=321228 https://bitcointalk.org/index.php?topic=321228 (alice and bob can be played by the same party for a cross chain transaction). There are some additional timing considerations for reorg safety when multiple chains are involved, but simply delaying all chain operations by enough blocks to make a reorg infeasible should be sufficient.