My husband has a block on purchases and he is deployed so I am unable to ask him what the password is. My son wants to use a gift card and I can’t add it because of the block. I also bought a new PS4 and tried to set It up as the primary but it wouldn’t let me use his account name. If his account is under my husbands account will I be able to login to the new system?
It sounds like your partner has set this up as a Sub Account. Basically, the Primary account (your partner's), is the one managing the Sub account (your son's), and without the permissions of the Primary account, you cannot change anything in the Sub account.
As for setting up the account on a separate PS4 system; you will not be able to "recreate" your son's account. You should be able to log in to your son's account, but again, the permissions set by the Primary account (your partner's), it will still have the same blocks on purchasing.
You could create a whole new account, as a Primary account on the same system, however, this account will run separately from your Partner's and your Son's accounts. Any purchases, downloads, or gift cards added to this new account will only run on this account alone.