“Seed” is obviously semantics guys..

The answer is if you found or derived private keys for those addresses, you need to pre-arrange trades for them with an OTC desk or two to lock in a price. As soon as the coins are moved the entire market will be aware and reprice the asset based on the expanded supply.

OTC desks typically wont ask which address the funds are coming from so dont tell them the whole amount. Just make the trades after setting it up.

This is assuming you want fiat currency, not everyone does.