Integrating an attendance management system into your existing MERN stack college management system requires attention both the frontend (React) and the backend (Node.js, Express, and MongoDB). You will need to manage student and teacher interactions with the attendance data and visualize this with charts. Here’s a step-by-step guide to help you through process:

1. Database Design

Start by designing your MongoDB schema to accommodate attendance records.

Attendance Schema Example:

const AttendanceSchema = new mongoose.Schema({
  studentId: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Student',
    required: true  },
  date: {
    type: Date,
    required: true
  },
  period: {
 type: String,
    enum: ['Theory', 'Lab'],
    required: true
  },
  present: {
    type Boolean,
    required: true
  },
  subject:    type: String,
    required: true
  }
  // More fields can be included as per requirement

Here, studentId references the Student collection, and you have fields for date, period (like theory or lab), presence status, and the subject nameStudent Schema Modification: If not already present, ensure there is a reference to attendance records in the Student schema.

2. Backend Setup

Write APIs to handle CRUD operations for attendance.

Create Attendance Record API:

• Endpoint could be POST /api/attendance
• Accept details like student ID, date,, and presence status.
• Make sure to provide proper authentication and authorization to secure your data.

Fetch Attendance Records API:

• Endpoint could be GET /api/attendance/:student
• Retrieves attendance for a specific student.
• Could be filtered further by date range or subject.

3. Frontend Changes

In your React application, implements for different roles.

For Students:

• A dashboard to view their own attendance record.
• Use chart libraries like Chart.js or Recharts to visualize attendance data.

For Teachers:

• A dashboard to mark attendance for students.
• Possibly an interface to view attendance analytics (like percentage present per week).

For Admin/HOD:

• A management page to oversee all attendance data.
• to approve or modify attendance records if required.

4. Marking Attendance

Create a UI component (such as a form or table) that allows teachers to mark present or absent.

Bulk Attendance Option:

• Consider a feature that allows marking the entire class or batch (especially for theory classes).
• Have checks to prevent accidental marking and easy ways to correct mistakes.

5. Attendance Analytics

Implement analytics features using aggregation queries in MongoDB to compute attendance statistics.

Creating Charts: Use a React chart library to display attendance data on the frontend.

// Aggregation example for attendance percentage per subject
Attendance.aggregate([
  { $match: { studentId: /* specific studentId */ } },
 { $group: {
    _id: '$subject',
 totalClasses: { $sum: 1 },
    attendedClasses: { $sum: { $cond:present', 1, 0] } }
  }}

6. Attendance Verification

When handling a large number of students, ensure your attendance marking is accurate.

• Review systems to allow to contest errors.
• Time stamps to track when attendance was marked.

7. Testing

Thoroughly test your attendance management with mock data.

• Simulate cases for individual students and large batches.
• Ensure performance is not hindered with extensive data.

8. Deployment

Once everything is tested, deploy the changes to your live carefully.

• Preferably introduce the new feature when attendance marking is not critical, to allow for adjustment time.

Additional Tips:

• User Validation: Make sure to properly validate the user input to prevent any corrupt data entry.
• Scalability: Consider using indexing in MongoDB for fields that you query often, this ensures scalability.
• Documentation: Document your APIs and functions which will be useful for future developers.
• Error Handling: Robust error handling on both the client and server sides for a seamless user experience.
• Authentication and Security: Secure your APIs against unauthorized access.

With a project this size, ensure that you have version control (such as git) in place, and consider implementing continuous integration/deployment (CI/CD) for smoother transitions. Keep in mind the importance of responsive designs if your app is going to be accessed across various devices, and accessibility to make sure all students and faculty can use your system with ease.