.How can I Create a new identifier manually and enable it to show in find a patient
if you want the Primary Identifier to be manually entered rather than Auto generated , overide this config here https://github.com/openmrs/openmrs-module-registrationapp/blob/master/omod/src/main/resources/apps/registrationappAppTemplates.json#L37-L39.
If you want to add another field of a manualy entered Identifier on top of the Auto generated , you can add it as a personal attribute and follow the steps below to add it to your custom registration app definiton. NB For it to appear in the find a patient, you set that configuration right when creating the personal attribute. see https://wiki.openmrs.org/display/docs/Managing+Person+Attribute+Types