Reusing an old Multibit wallet

[Quail]

When I first got into bitcoin back in the day I used Multibit. I only ever had a small amount of bitcoin, but without going into too much detail I lost a few and ignored cryptocurrency for a while. When I regained interest I found that Multibit was no longer supported, so I sent my bitcoin to an Electrum wallet and subsequently moved to a hardware wallet.

I've just found out there may be a chance of regaining access to the bitcoin I lost back in the day if I can prove that the Multibit wallet was mine. I've been requested to make a small transaction from the same address of the Multibit wallet.

Could I deposit some bitcoin back to my Multibit wallet and send from there, or will there be issues? The max fees are 50k satoshi per kb - is that still sufficient today?

Alternatively, I still have old backups, including the .key .info and .wallet files from Multibit. Can I sweep/export these to another client? Are there problems/risks doing this with a .wallet file? Will I still have the same address if I try to sweep these to electrum?

Any help would be hugely appreciated. I don't have a huge amount but I'd be happy to help out anyone who can assist me.
Cheers

[1715262120]

1715262120

[1715262120]

1715262120

[1715262120]

1715262120

[1715262120]

1715262120

[OmegaStarScream]

Multibit developers have no access to your funds so I'm not sure what do you mean by "prove" that you had bitcoins. If you have the .key though, you should be able to open it using any text editor since It's a plaintext file and then, just take the private keys and sweep them to your Electrum wallet. If there is a password on the file, import the .key first and then export it again without the password.

[Quail]

Multibit developers have no access to your funds so I'm not sure what do you mean by "prove" that you had bitcoins. If you have the .key though, you should be able to open it using any text editor since It's a plaintext file and then, just take the private keys and sweep them to your Electrum wallet. If there is a password on the file, import the .key first and then export it again without the password.

I need to make a small transaction from my old wallet in order to prove it is mine.

If I sweep the keys in Electrum and then make a transaction I'll still have the same address, right? I have the password and all info. I realise I'm probably being really dense but I don't want to mess up anything here... thanks.

[OmegaStarScream]

To prove ownership over an address, you could sign a message using Multibit itself. Sweeping is not like importing, you will be basically sending funds from the addresses associated with the private keys to your Electrum addresses. Importing on the other hand will make you stay with the same address (these imported addresses won't be part of your Electrum seed, while the sweeped one will be).

[Quail]

Ok, thanks, guess sweeping isn't an option then. I've signed a message and hopefully that proves to be enough. If not I'll import into electrum.

Thanks for the help!