No, this is not possible.
You can only manage coins in BTC Direct which you have purchased through us. We do this for security reasons. For instance, is your BTC Direct account hacked? Then a hacker cannot just send your coins to their wallet. Selling your coins and withdrawing your balance to your own bank account is the only thing they can do.
If you still want to keep all your coins in BTC Direct, first sell the coins from your wallet. With the amount on your bank account, you can then buy the same coins via BTC Direct.
This way, you can manage all your coins in one place.