Dr, once a VFR becomes 'known' to an ATC it must be passed as traffic to an IFR aircraft if it affects it.
On our group VFR flight plan amendments passed to ATC on VHF are recorded on a scratch pad with the time received. The time is noted to make it easier to track down on the recording should Censar (or anybody else) require the information. If you amend your SARTIME via ATC or flight watch it is passed via the AFTN to Censar.