Or ask the current registrar to play DNS for the domain.
They need to create a wildcard A record pointing to your ip address.
that way you can enter everything before the domain.com and it all goes to your address. (e.g. www.domain.com
-> your ip | blablabla.domain.com -> your ip.)
Also.. if you want to run mail for the domain... let de DNS admin create the correct MX records (pointing to your ip).