SM is already late, as were the previous 2 filers. Assuming the Form 8-A of 9/28 was the trigger........and I believe it was......Form 3 calls for filing "no later than the effective date of the registration statement".
RME should be filing a Form 3 as "beneficial owner of greater than 10% of a class of securities registered under Section 12 of the Exchange Act"...........which occurred when the 8-A registered the Class B shares.
Signature only needs to file if its current holdings exceed 10% of the outstanding common. Two numbers that I believe may be unknown to any one person.