The best we can do is give them the 800-829-1040 and let them call for themselves, its very important for them to know what is happening is not within our control.
Be careful, if the corporation assumes Sole Prop liabilties which are in excess of the FMV of the Sole Prop assets it will trigger taxable gain,
which happened to a new restaurant client of mine years ago.
Both the Sch C individual as transferor and the S Corp as transferee will each attach statements. https://www.law.cornell.edu/cfr/text/26/1.351-3
Shareholder receiving stock must file statement with return for the year of the transfer under Treas. Reg. §1.351-3(a)
Corporation must file a statement with its return for the year of the transfer under Treas. Reg. § 1.351-3(b)
Both must maintain permanent records to determine subsequent gain or loss