You create domestic DVs as simply as creating a SubCA to your CVCA, using a SubCA certificate profile.
You can sign foreign DVs by treating them as regular End Entities. Simply create an end entity and choose a SubCA certificate profiles when adding the end entity. You can then process the certificate requests received by the foreign DV as a regular end entity certificate request:
Using the public web GUI
Using the WS cli, clientToolBox CvcWsRaCli
Using the WS-API cvcRequest method from your own client
You can also create foreign DVs as external SubCAs, but a benefit of handling foreign DVs as end entities is that you can process and renew them using the same WS-API as you can use for inspection systems.
You can create a DV to be signed by a foreign CVCA by creating a new CA and selecting Signed By=External CA. You need the CVCA certificate of the foreign CVCA to create the request to be sent. When creating this CA a self-signed CV certificate request is created.
You can at any time create a CV certificate request from a DV by going into Edit Certificate Authorities and click Make Certificate Request. This generates a CSR created by the CAs keystore. When receiving the signed certificate back, you can feed that to your IS-system. There is no need (or way) to import it into EJBCA.
You can renew a DV by going into Edit Certificate Authorities and click Renew CA. By uploading the CA certificate supposed to sign the certificate, you can get a new CSR created. You can import the received certificate by clicking Receive Certificate Response. You only have to (or can) import one issued certificate to make your DV operational. If you get a DV signed by multiple CVCAs you can distribute the other, than the main, DV certificate to the IS's (or AT or ST) by other means.
By filling in the CA tokens password and checking the box Renew Keys the DV will generate new keys. This works for both soft CA tokens and PKCS#11 CA tokens. The renewal CSR is not signed with the old keys, but that can be done manually.
DVs have short validity periods, and it may be good to have them automatically renewed. There is a service, Renew CA Service, to automatically renew CAs. The User's Guide contain more information about this service.