Op do it but do it YOUR way
loads of templates on internet for santa letters and headers and do your own.
I got a sweet elf from ikea we call Elly.
She came with a note we created saying something like...
" Dear X we have noticed from our records you have never had an elf visit you, frm time to time, we like to send out new elves into the work place to feed back ideas about the children's likes and dislikes, this helps us tailor presents to their personalities more. HOwever please note as these are new elves they can be prone to mischief. Whilst we fully expect some cheek - any major misdemeanors must be reported back to us at the north pole.
Elly will return with us on the sleigh xmas eve night, you must not touch her lest you spoil her special fragile magic.
Noting about spying etc and our elf is cute and not sinister looking
I also only did it for ONE WEEK. which was hard enough believe me.
Elly last came three years ago.
She will be visiting again for a short while this year as youngest will be 4.
My older dd LOVED IT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
We had shaving foam all over car with merry xmas in it - elly painted their adn our faces in the night.....the green wee in the loo....she loved it!!
so do it - but your own way what you can manage