[littlefrog]

Best to start with fresh medium than to try to add nutrients. I don't think it is worth the effort, and I'm not sure it would work anyway.

One of the main reasons to replate is to move your crowded protocorms onto a medium that supports root and top growth. Plus, moving them while they are still protocorms avoids damaging roots. You may need to replate twice, especially with heavily sown mother flasks (seems to be a problem with cattleyas and some hybrid phals).

It is certainly nice to replate into a nice pattern in your flask, it is prettier and an evenly spaced pattern lets the seedlings develop evenly. Plus if you ever want to sell them they sell better... But, just throwing them in haphazardly is better than not replating.