HCA: Hermit Crab Association

So I have had my 2 hermit crabs for almost 2 months. I have them in a 10 gallon tank. One hermit has been buried for probably a week. While the other is out and about. I am getting them a 20 gallon tank today. I am very invested at this point and wanted to upgrade and give them more space. So my question is I am moving the one hermit who is out. Moving the heating mat. I know I shouldn't dig the other out. Would he be fine until he comes out to move him as well?

I wouldn't make any changes till' he's out, any little change could be stressful to the molting crab. Just leave them in the ten gallon and don't move anything till' they are both out and ready. You want to make it as stress-free as possible, even if that means waiting a bit longer.