Collecting Assignment fee at closing on HUD-1

I really do not do many contract assignment and when I have they were small fees that were easy to collect.
Now I have a big assignment fee of 30K and the buyer does not have the cash. He wants to put it in the price and pay it at the closing table thru the sellers proceeds. I know many investors are collecting the fees at the closing table but not sure how.

My broker says we can not do it as a marketng fee and I am not a realtor so no commissions. Any suggestions or thoughts on how others are doing this? Should I just get hold of the title company and ask.