My question involves collection proceedings in the State of: Florida

My friend is being sued for $58,000 for an unpaid credit card. Some company bought the debt from some big bank who gave the credit card. She wants me to negotiate with the lawyer of the company that bought the debt for her. But when I called the lawyer to do just that she (the lawyer for the debt buyer, also a female) said they needed written permission from me saying it's OK for me to talk to them about her case. And they said to do that I need to put a letter in the mail to them that days I can talk about the case with them. Here's the question: Is it legal for me to use an alias in that letter to them, and will what I say be admissible in court? I don't want to give them my real name.