Select component Customization to add values (Data Source Values) in runtime of submitting form

[MoraParamesh5b0]

I have a requirement on select components as
We have select component with options/Data Source Values (Ex: opt1, opt2, opt3)
Now I'm going to submit the form in formio tag, But unfortunately opt4 is not in the select component list values/Data Source Values.
So I have to provide Add button (+) at select component like below to add options that missed at the time of submission
even if the values getting from the RestApi/URl for those also i have to add missed Data Source Values