Parents: Do you RSVP to birthday party invites?

Parents: do you RSVP to birthday party invites?

For context: this relates to RSVPs for your children's friends' birthday parties.

This has been a bit of a debate in my circles. Interested to know if this is a UK thing or not. I've asked in a few places.

When your child receives a birthday party invitation and you don't plan to attend, do you RSVP 'no' so they know you can't attend or do you ghost the invitation and not reply / hope the hosts figure it out?