Hello, the account number on his ID card has nothing to do with you. You can re-use your ID card for business directly, but if you re-install, it will be equivalent to a new broadband port, and you must pay the initial installation fee again (depending on whether there are preferential activities free of the initial installation fee in the local area).
If you plan to use his account, you don't need to pay the installation fee, just log in to the online business hall and pay the arrears.
I hope my reply can answer your question.