HCA: Hermit Crab Association

Hi! I'm new to hermit crab care (I've had mine about two months) and I'm dealing with my first hermit crab molt. I have two that I just call the little guy and big guy due to their significant size difference and it's easy to tell them apart as they've never switched their shells since I got them although I've provided an abundant amount. Into my problem- my little guy seems to be having his first molt in my crabitat.

I'm worried about him as I was in the habitat the other day cleaning dirt out of shells as to try and make them more accessible for him once he was done with his molt and I found that a very large shell that my crabs have put next to the saltwater bowl had some resistance when I went to pick it up so I instantly stopped, as I think my little crab may be molting in there as at this point I haven't seen him on the surface in a bit over a week, and I thought I saw his legs poking out. for reference id say he's a bit bigger than a quarter and this shell is about golf ball-sized. is it healthy for him to be molting in there? i didn't realize he was in there, I thought he was underneath his saltwater dish as I accidentally uncovered him under there a week ago, so I have not stopped my big crab from just walking over there (he isn't a digger and he lost his fighting claw before I got him so I haven't been too worried as I did not know that you should separate molting crabs).

On top of all of this I have heard chirping coming from the crabitat at night, which I have never heard before little guy started to molt! im worried that its a sign that my bigger crab is messing with my molting crab (such as climbing on the shell he's possibly molting in) or that my bigger crab is lonely or agitated (he has not been as active since my small one went to molt). Does anyone have any suggestions on what I should do? i know now I should have separated my little one as soon as he began digging around and showing signs of molting but unfortunately I did not know that until it was too late. Any advice would be extremely appreciated, as well as any responses that might help me answer my questions. Thanks!

Welcome to the forum!
No, you shouldn't move a crab into a different tank to molt. As long as your tank is not overcrowded, and you have deep enough substrate, it is better to leave them in their home tank. Your substrate should be at least three times as deep as your largest crab. And depending on the size of your crabs as to how many you can have in a tank of what size.
If your crab is not underground when he molts, he is at risk because he is vulnerable to the other one. A surface molting crab needs to be isolated from other crabs. You can do this in the main tank, either with a small container to put him in and leave in the tank so the conditions are ideal. Or you can cut down a 2L pop bottle and push it into the sub so he is protected. But you need to confirm that he is actually on the surface before you do that, or else you could disturb him underground.

I have a 10G tank, and the substrate was deeper but the crabs like to dig in the corners so this particular area I believe my crab is possibly in is a bit shallow. is there any good way for me to confirm that he's molting in the shell rather than underground? and if I put in a pop bottle to create a barrier, would I need to still supply my molting crab with saltwater?

I would pick up the shell and have a good look to see if the crab is inside or not.