Relation one-to-one: bug or misunderstanding

Hello!

I have a question about the concept of one-to-one relation that can be used in forms.

I will you use a simple example for my question; a system with members. Those members have only one card each.

It's seems that for Zoho, one-to-one means:
- One card belongs to one member
- One member can have one or more cards

For me, one-to-one means that:
- One card belongs to one member
- One member can have only one card

The solution I need is the second. So, is it a misunderstanding of me for the relation one-to-one? There is a way to obtain what I want? Informations about members and cards in the same table maybe?

Thanks and regards,

Julien