HCA: Hermit Crab Association

I am new to this I have 4 hermit crabs 3 small and 1 large I was given the late one and one small one and I purchased the other two small ones a couple days after getting the other two when I got the first two they were in a cage way to small without the proper depth of soil so I went and purchased a large tank , shell's, and all the other items needed during that time I of course couldn't resist the other 2 so I brought everything g home set up the tank not even a hour later one of the new ones switched shells then later that night the second one did as for the 2 I had first the large one buried himself the next night and the small one that came with him won't leave his side he either digs a tiny spot right above him and lays down on him or he digs right next to him and lays next to him. He did not ever show any signs that he was ready to molt he just one night dug a hole and that was it I checked on him once he is alive but after that I just left him be .could he be molting or is he just stressed from all the new change also for the first day or two in the new cage it took a bit to regulate the temperature and keep it from dropping. So my question is . is he molting or stressed an if he is molting is his little friend going to bother him? And if he is stressed what can I do to help him?

Most new crabs need some time to destress. This means they will dig or hide and stuff to get used to their new environment. I would just suggest not bothering them (like picking them up or anything) and give them some time to get used to everything.
Also if he decides to go and dig down to molt he should be okay. I don’t think the other one will bother him. I have crabs that stick together and molt fine.
But yeah they probably just need their time to destress so they might dig down and be gone for a while and they will be destressing and /or molting.

There is really no way to know if they are molting or de-stressing, or just digging around for fun. Time will tell.
As long as you have enough substrate, and your tank is not over crowded, the other crabs should not bother the ones who are under ground.