If you are billing under a group name and tax ID#, and then going to bill for the NP & LCSW's under that tax ID# then you individually cannot become credentialed with Medicare, but it sounds like you need to as a group provider. Then you would credential the NP and the LCSW's individually but reassign their benefits to your group. If they are already credentialed with Medicare you would just need to reassign their benefits to your group.
(Your credentials don't matter for credentialing as a group, you are the owner, but you will have a recognized provider under your group, and that is what matters.)
Michele