Just to be sure that is legit or not

I've organized a new Giveaway on the Facebook Section, however i wanna update (via PM if possible), all the users that have joined that there is a new Giveaway...

So...can i send the same PM (with the new giveaway's link) to all the users who have joined in my old giveaway?

Please let me know, i don't wanna "create" problems ecc
Thank you so much!