Welcome to the Q&A Forum

Your subdomains will be treated as entirely separate websites in the eyes of Google, as Matt Cutts explains: https://www.youtube.com/watch?v=_MswMYk05tk In simple words, if you have https://mywebsite.com https://blog.mywebsite.com These are 2 different sites or properties according to Google, so in your case, you can move, migrate or update your subdomain and this will not affect the parent domain. Regards