The phrase "add in extra" is correct and usable in written English.
It can be used when you want to include additional items or information in a list or discussion.
Example: "If you want to enhance the recipe, you can add in extra spices for more flavor."
Alternatives: "include additional" or "insert more".
You can add in extra parameters like whether there is access to the outdoors, nearby train stations or gyms and yoga studios.
You can even add in extra media like a video from YouTube or more images simply by searching on google within the app itself.
So you only let 100 people buy the product [at the outset] and add in extra provisions and securities to ensure they have a great experience and you're smart about the liabilities.
Add in extra fees that aren't typically covered in all-inclusive rates, like laundry, fitness classes and premium beverages, and it's easy to see why it's essential to anticipate not-so-obvious expenses and strategize accordingly.
There can be a tendency to add in extra "burdens" which seem a good idea at the time, but may be counterproductive if many trainees find themselves unable to complete their studies.
Don't add in extra vocab words to sound more intelligent.
Dispensers are included on some, automatically adding in extra ingredients such as nuts and dried fruit at the optimum time.
Borrowers can achieve similar results by paying down the balance when they refinance, by adding in extra cash — 21 percent of borrowers did so in recent months, Freddie Mac found.
When you take your dog to the park, a stroll around the block or a running session, you're adding in extra calories burnt that you're not even thinking about.
Alternatively, since a lot of the models are learned independently of each other, it is fairly straightforward to parallelize the computation and reduce the total running time by adding in extra machines.
