I had a similar problem with the Android Wallet which is also based on bitcoinj. I wanted to transfer my backed up wallet from my old phone to my new phone. The problem I had was that I wanted to take advantage of the new wallet words, as well as have my old addresses with me.

The only thing I could come up with is just sending the funds to my new wallet and deleting the old one.

I figured that no one would need to send me money to the old addresses. And, if they did, I would have to tell them that the addresses were compromised or that I didn't have access to them anymore. Moreover, because of the bug on Android, my old wallet made an automatic transaction flagging some old addresses as compromised.

The new wallets (and Bitcoin core itself) encourage the use of only one address per transaction. So, I think that transferring funds to the new wallet is the easiest way to go.

Hope this helps.

The files you have from multibit-HD (old) must have a version. Search for a .exe or .dll file. Check it's version. Download that version of Multibit-HD.

You can find the file version by

Right Click > Properties > Details

After you download that version, install it. Then replace some files. I can't really say which ones because I never encountered such weird problem.

Also, there is a huge possibility that this might not work and you have lost your BTC for ever. But nothing is wrong in trying , right ?

Try this, and tell me what happened. I might be able to help you more if we can talk more privately.

Tell me the results if it doesn't work, I will e-mail you for more information.