How to create table where primary key = primary key from another table

Question

For example I have table user

public class User
{
public int UserId {get;set;}
public string Name {get;set;}
}

And I have table

public class UserPlugin1
{
public int UserId {get;set;}
...
}

public class UserPlugin2
{
public int UserId {get;set;}
...
}

The main thing that field UserId in plugin table should be the same as in User Table.

I tried this but it failed

public class UserPlugin1
{
public User UserId {get;set;}
...
}

Of course I can create standard primary key UserPluginId and use UserId as foreign key, but in this case i will have unneccessary field UserPluginId. That's why i decided that idea to make field wich id will be from user table is better.

public class UserPlugin1
{
public UserPluginId {get;set;}
public User UserId {get;set;}
...
}

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