As the holder of an ATPL you have a Night Qualification. Night ratings are a thing of the past. If you obtained your FI rating on the basis of a Service QFI qualification, it will be unrestricted, in other words, unless it says No Night flying in Part XII, then you can give instruction in night flying.
As your IR is Multi pilot, unless you also have a valid single pilot IR, then you will have to meet the 90 day recency requirement of one out of three take offs and landings in the past 90 days at night,if you wish to carry passengers. A student is of course crew and not a passenger.
[This message has been edited by Noggin (edited 25 November 2000).]