http://www.asppa-net.org/Portals/2/PDFs/GAC/Comment%20Letter/IRS_Compliance_Questions_Comment_Letter5.31.16.pdf
Especially read the piece about trust EIN's. It sounds almost rude and snarky, but then it is so true which makes it very reasonable to say...
HAve I ever had this ridiculous request in particular? No. Have I ever had ridiculous requests for which I could not fathom any rationale? Absolutely. There is no telling what client's passions will convince them of.