How to name these helper functions?

public class Member
{
    Team team;
    int p;

    public void GoToTeam(Team team)  // 1. how to name it?
    {
        this.team = team;
        p = team.GetHashCode();     // some setup for team changing
    }

    public void AddMember_wrapper(Team team)    // 2. most software users are members, do I need this?
    {
        team.AddMember(this);
    }
}

public class Team
{
    List<Member> members = new();

    public void AddMember(Member member)
    {
        members.Add(member);
        // and something more, member maps etc
    }
}

Member has a GoToTeam function, which cannot work alone, without being called by functions like AddMember.

How to name these helper function in c#, to prevent it to be called alone by mistake?

A good class design would help. Like always Team do action to lower hierachies.
But member is the basic action unit. Do I need a ugly member.AddTeam_wrapper()?

Is there a more straightforward way to do this?
Like __GoToTeam in other languages.

I'm working on composite patterns.
A lot of classes are hierachically structured.
Methods are used to change their relationship.

It's easy to use a half-function by mistake, without a detailed documentation.
I want a good naming convention to describe these public methods and public but not standalone methods.

Thank you!