We are using Altium database library. But our concern is if an engineer is working on the library then another engineer who needs to add new part in the same database have to wait. Is there a way to add the component in the same library by two or more persons at a time?
You don't edit the .dblib file, you edit the data in the database. As long as the users refresh the database after each change, you should be fine. Even if you don't, Altium refreshes it by itself, usually on start up. Also, schematic components that were already placed get updated.