Licensing when not working

Like everything else about nursing, the requirements vary somewhat from state to state, so check with your BON to get the specifics for your state. I believe that some states require you work/practice some minimum amount of hours in order to maintain an active license. You may also be required to complete a "refresher course" when you want to return to practice, depending on how long you were away from nursing.

Of course you can be both an RD and an RN, as long as you meet the requirements to maintain both credentials. The time you spend working as an RD won't count as hours of nursing practice, of course, and vice versa ... (You don't actually sign "RD, RN" after your name, do you? Why bother to use more than the credential for the job you're actually working at the time?)

Be aware that you will not be a v. competitive/attractive job candidate after staying home for a number of years, esp. with the minimal amount of experience you have now, and you will have a very hard time getting facilities to treat you as a "new grad" (you may have a very hard time finding a job, period). A lot of people work at least a minimum amount of part-time hours while raising their kids in order to avoid being completely out of nursing for an extended period -- that's something to consider.