A change to reporting is due for release in Mosaic reports 23.1, due February 2023, to allow for this information to be reported from forms in Mosaic. This will allow for the reporting requirements to be met for 22/23 onwards.
You can add a radio button- or drop-down list questions to your existing care leaver contact forms to capture the birthday date to allow for this reporting. The workflow step for the post 21 contact must be separate from other care leaver contact recording. The logic for the relevant tables and reports will be updated in Mosaic Reports 23.1 to capture the latest information recorded within the reporting period for 21+, while remaining as it is currently for 16-21 recording.
Filters will be introduced in Mosaic Reports 23.1 to allow you to identify the relevant form questions, and the existing groups will be updated to allow the form answers to be categorised alongside the current care leavers screen data. The care leaver screen functionality will not change, but precedence will be given in this case to the form answers.