You can easily validate users with the Validate BVN API. You do not have to identify, since you can validate.
How it works
What is majorly required of your users is the BVN, and if you want to validate further, you can also ask for the First name, Last Name, and Date of Birth.
You will get a true response if the BVN is valid, and you will also get a true response if the First Name, Last Name, Date of Birth matches. The response will be false if otherwise.
There is also a confidence value for the first name and last name, incase the parameter passed is not exactly what is in the response. This is to further validate, and you can make your own decision off the confidence values.
This can easily be used in the onboarding process. And you do not have to alter your process if you previously included BVN.