The suggestion is to postpone creating this new message until the implementation of PTLCs (Point Time-Locked Contracts), as a similar mechanism will likely be required for exchanging partial signatures for PTLCs. This approach is supported by previously detailed documentation on PTLCs, which can be found in an old writeup. Furthermore, the cited writeup suggests a method that allows for the Claim-PTLC-Success transactions to be transitioned to version 3 without necessitating additional modifications. Adopting this methodology would simultaneously address two separate issues, effectively streamlining the process and ensuring efficiency in the development of these cryptographic contracts within the Lightning Network framework.