Distribution Lists
Distribution lists
In Office365 Distribution Lists can either be static (members added/removed manually) or dynamic (membership populated automatically based on role).
Static Lists
Static lists can be managed by Group Owners.
Office365 Groups
These can be managed by Office365 Group owners. Once you are an owner you can manage joiners and leavers in that distribution list using the following article from Microsoft
Support Requests
GSL's or their appointed technology champion should contact the Office 365 Team for support.