Try it! From your DigiByte wallet: 1. help, 2. Debug window, 3. console   then type, importprivkey "5yourveryveryveryverylongprivatekeystring" ( the XVG private key, I assume you already have).

I have no idea about XVG wallets but if it is qt-like, from the console you will need to do something like this:
    Click on 'help' in the menu bar (top right)
    Click on 'debug window'
    Select the 'console' tab
    If your wallet is protected by a passphrase (i.e. you have to enter a passphrase before you can send) unlock it by typing

    walletpassphrase "your walletpassphrase here" 600
    dumpprivkey "DAkF9qw1sMygb6pHZWuhZwTgxSsRrb3uJw"
    This will return the private key

    Once you have your private key if you had to unlock your wallet you can relock it by exiting or typing:

    walletlock

you will need to open your DGB wallet with the passphrase command too, if your wallet is protected with a passphrase.