Is there a way to find out if companies have employed Sell Side Brokers?

Hi,

I am working in an Investment Firm, we mainly deal with Buy side sourcing suitable investable companies for our clients.
I wanted to ask you guys if there was any way I could asses if some of our target companies have sell side brokers behind them.

This enquiry simply has to do with analyzing our fee structure, as the companies we have on our slate pay us a fee once we complete the full investment. So we want to assess our fees for companies based on if they either came to us directly or through a sell side broker (which demand a fee from them as well)

Thanks