You should cancel the meeting and shop around for a cheaper legal service.
Look over these forms. These are the basic forms that will be used.
The real issue is making your best effort to notify the biological mother. If you ask your mutual acquaintances, you should be able to find her. That will eliminate a major hurdle.
Good luck.
In the meantime, you should also create a document with bullet points stating
each child's age, name, birthplace, parents
history with biological parents
dates and events when you gained custody of them
your address, occupation, basic vital info
any other info you think is relevant
Finally, if your kids are twelve they will need to consent to the adoption.
Good luck, stay organized, don't spend more money than you must. Take the time to look over the court forms, especially pages 10-20. Use google to look up any terms that may be unfamiliar to you.
Lotsa love.