使用WTForms，我怎么能让一个字段是隐藏的选择，但显示为2个复选框？

from wtforms import Form, BooleanField, HiddenField
from wtforms.widgets import CheckboxInput

class MyForm(Form):
    hidden_field = HiddenField()
    checkbox_field1 = BooleanField(widget=CheckboxInput())
    checkbox_field2 = BooleanField(widget=CheckboxInput())

from flask import Flask, render_template, request

app = Flask(__name__)

@app.route('/', methods=['GET', 'POST'])
def index():
    form = MyForm(request.form)
    form.hidden_field.data = 'hidden value'
    
    if request.method == 'POST' and form.validate():
        # 处理表单提交
        
    return render_template('index.html', form=form)

<form method="POST" action="/">
    {{ form.hidden_field() }}
    {{ form.checkbox_field1() }}
    {{ form.checkbox_field2() }}
    <input type="submit" value="Submit">
</form>