I seem to recall (it was over a year ago, lol) a question on the online i-130 if the beneficiary was in the USA, if you answered yes to that (even if they were there temporarily), you would have gone down the adjusting path.
As I stated with more details:
read the instructions for i-824:
https://www.uscis.gov/sites/default/files/document/forms/i-824instr.pdf
fill in & print the i-824 (fill this in as the petitioner):
https://www.uscis.gov/sites/default/files/document/forms/i-824.pdf
make sure you sign it physically.
see the fee for this form in the instruction link, make sure you include that fee in what you send
mail in the form
wait for the welcome email from the NVC.