Now, if the agreeement to settle is predicated on ALL parties settling, or NO parties settling, a sensible position for TPL/PTSC to take since they wouldn't want to continue the expensive legal process for one defendant only, it would require an assurance that ALL parties signed. However, since each was signing a separate license, what mechanism can the court use that would encumber Toshiba to remain in the process, if they were to utlimately sign the license, but for some reason Matsushita balked. An MOU that outlined the responsiblity that EACH defendant must sign a license agreement before any of the parties can consider the case dismissed would make sense. Otherwise, legally, if Toshiba signed a license, with an agreement that that would dismiss them from the proceedings, but Matsushita didn't, it seems like without an overiding agreement that bound them to Matsushita's signing, TPL/PTSC and utlimately the court would be hard pressed to enforce that they remain part of a case whereby they signed a license that in essense released them from that infringement argument.
I have just one slight problem with this line of thought in that ALL signed and as such there would be no reason for an MOU as you postulate, nor the Court retaining jurisdiction.
Please remember that NEC Electronics America signed separately.
Be well