HCA: Hermit Crab Association

My substrate has settled somewhat & it needs more. Is it safe to add my sand/cocofiber mix on top of the substrate that is already in my tank? I thought I read that I can if I do it in small amounts a little at a time. I have some crabs under & molting. 2 days ago I got 2 teenies. The rest are small & medium sized. The new crabs are destressing I think. Will the teenies be alright if I add or could it be a problem for them?

Thank you.

Adding more substrate with crabs destressing or even molting is perfectly fine. Just add a little more at a time, about 1/2" per day, and don't pack it down.