A hypothetical example of such scenario can be - A mother/father with two kids wants to book lessons for both the kids; can those students's information be I entered setting up a separate email ID?
Well, there is NO way multiple client entries can be made with the same email id. Email id is the unique identification recognized by the Appointy system and is used to differentiate between 2 users. You can create a custom questionnaire for the users/elderly people/family member's information. So for example, when parent takes an appointment on behalf of their siblings, you (as an admin) will have the information of both the parent and the siblings as well.
Here's an article for more information on Custom Forms. Click here for more information on setting up custom questionnaire.
In order to notify the additional info to the parents you can use the **"CUSTOM FORM SMARTY TAG"** under confirmation email (Settings --> Customization --> Email customization) which will enable you to send the requisite info of that particular child as in this case.
Should you need any assistance in setting it up, please do not hesitate to contact us via email. You can reach us out at firstname.lastname@example.org