In my mind you have two options here...
1) don't give them anything staff moan they do not know anything as they havn't been told = You department looks bad as you hadn't
2) Give them some a welcome package do the induction. The staff may still moan but you can point out that was covered in induction and in the welcome pack (you have read it). = Your department looks good even in the face of staff who may be inefficient..