There may be a way to automate the manual replies while keeping your existing topic-local [calendar] workflow.
One possibility would be to use a dedicated Discourse user with reply-by-email enabled, then have something such as Power Automate or an Azure Logic App generate the individual dated replies and send them into the calendar topic by email.
For example, a weekly appointment with an end date could be expanded by the automation into the required individual replies, so parents would still see one normal topic calendar rather than separate Event topics.
There are a few details around Discourse’s per-user reply-by-email keys that would need to be set up carefully, so this topic probably isn’t the best place to go through the configuration.
If that approach would be useful to you, I’m happy to help work through it in a separate Meta topic.