Sync between fields and add options to single select field if option doesn't exists

[kk4065896]

Hi,

I have a use case: Two fields in the same issue 'Summary' and 'Single select cf'. I have to sync both fields and make single select field read-only. If user updated summary field, same value should update in single select field. If the value doesn't existing in single select field it should create automatically and update with the value. Please help me to achieve functionality.