Update ALL records that fit criteria

Update ALL records that fit criteria

In my form I will have multiple records that fit my fetch criteria of:
Name.first_name == input.Participant_s_Name.first_name && Name.last_name == input.Participant_s_Name.last_name && DOB == input.Participant_s_DOB

On successful submission of another form, I am trying to update ALL of the records that have the same name and DOB of the record that was just created. But it is only updating one record. Any thoughts on how I can fix this?

This is the script:

count = 0;
fetchRec = Holiday_Clinic_Daily_Bookings_Subform[Name.first_name == input.Participant_s_Name.first_name && Name.last_name == input.Participant_s_Name.last_name && DOB == input.Participant_s_DOB];
if(fetchRec.count() > 0)
{
fetchRec.Waiver="Yes";
}

The below image shows that only one record has been updated and the others have not.