Yes, you can mention her. However, if you wish to file for her green card and citizenship, you'll need to fill out and submit some additional forms on her behalf.
The first form you'll need to fill out for her is Form I-130. Then you'll also need to provide:
1. A copy of Form I-551 (green card) OR
2. A copy of your foreign passport bearing a stamp showing temporary evidence of permanent residence.
You'll also need to submit a copy of her birth certificate and some other supporting documentation, which you can find listed here at this link to the USCIS website:
Note, it is possible that you might be asked why she wasn't mentioned in your prior application paperwork, so just be prepared to share your answer for that in case it comes up, ie. you forgot, didn't know you were supposed to include her name, etc.
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