I think that is currently not possible. It is not possible to share credits between Skype usernames.
I have seen other posts about shared accounts. However, I have tried to sign into my husband's account as he purchased the unlimited callling monthly thinking we could share it...How can we do that?
You can simply use your husband’s account name and password.
you might run into trouble if you try to make simultaneous subscription calls when using more than one instance of that Skype Name