you will need to ensure that you update all your backups of wallet.dat as older versions of the wallet.dat will not be able to recover that private key as it was not created by the embedded seed.
Well I just realized this is key. I just wanted to avoid having to contact the chipmixer admin to change my address if I could avoid it since managers are too busy and so I am. There's also the nice feel of having an older coinbase for hodlers but I guess that's just a geeky thing.
Another reason was to have the key on my wallet so I don't need to keep track of an additional wallet (in this case the electrum wallet). Even if you move the coins and the electrum wallet is worth 0 after, you still want to have access to that private key. For instance lets say you sell these coins someday to buy a house, authorities may ask for origin of funds. The key must coincide with the moment where accrual happens, as in being able to prove it came from a legit activity (in this case, the address matching with the payment from the manager, so you can sign it and prove it).
I am just trying to stay ahead when it comes to taxes, trying to get everything in order. When BTC is worth $100k in a couple of years people will want to buy some property with it and then you must be ready for an audit and things like these can make the difference from avoided getting f*cked in the ass by the confiscator.
