YEs you can nest a sub , depth will depend on what you have created(;-) 3 is normal . BUT it will depend on if you use tool comp0 and HOW you use it as to IF it will work.
I have seen subs fail on the first nest and some that would go deep down the rabbit hole with no problems.
Just have to try it and see what you come up with.
Help is here, (;-) TP