LINQ “Where” condition -> change value of property

I have a list of meetings inside which I have another list of attendees.

Model similar to this –

public class Meeting
        public string Id { get; set; }
        public string Title { get; set; }
        public List<User> Users { get; set; }
        public DateTime StartTime { get; set; }
        public DateTime EndTime { get; set; }

I have list of Meeting

List<Meeting> meetings = GetMeetings();

Now I want to mask the Title of the meetings where one of the users is I can achieve this in multiple LINQ queries but I am looking for optimized LINQ query..

Can anyone help me with this?

What I tried –

var maskedMeetings = meetings.Where(x = x.Users.Any(a => a.Email.Equals(""))); 

meetings = appointments.Except(maskedMeetings).ToList();

maskedMeetings = maskedMeetings.Select(x => { x.Title = "Bot"; return x; }).ToList();

meetings = meetings.Concat(maskedMeetings).ToList();

Can anyone help me with optimized way of writing this query?