You can not add anything, after your return has been e-filed and accepted. You have to wait until your return is fully processed (you get your refund) and then file an amended return, if necessary.
You probably do not need to add anything, as a 1095-B seldom changes anything. If you answered (for the original filing) that you both had health insurance, and the 1095-B doesn't change that fact, you do not need to amend.