http://www.kccllc.net/documents/8817600/8817600210201000000000001.pdf Quote: " .. The Escrow CUSIPS were established solely to facilitate potential distributions, if any, ofshares of Reorganized WMI common stock; however, all shares of Reorganized Common Stock on deposit in the Disputed Equity Escrow have now been distributed and the Trust’s administrators do not expect that any additional distributions of common stock will be distributed to former beneficiaries of the Trust or holders of Escrow CUSIPS.Nevertheless, at the request of certain legacy shareholders, the Trust’s administrators agreed to keep the Escrow CUSIPS outstanding until the Trust’s dissolution .. "
=> So first let's wait till the Trust is dissolved. And also there is the question, if Escrows are really needed for distribution of any ("safe harbor") assets apart. I'm pretty sure that this can be also done without any Escrows, but with the information available at DTC.