Missing memberof attribute in person record under open directoy

Hi,

We have Apple Open Directory (will refere it as AOD henceforth) setup and is working fine as far as the user authentication is concerned.

We are trying to setup a fortinet utm for our office and setup group based policies using the AOD authentication.
The basic authentication using AOD is working fine. However when the UTM is trying to authenticate the users under groups, it is trying to search for the “memberof” attribute on person record.

I have done lot of google on this topic and came to know that AOD does not have this “memberof” attribute for person record. Rather it has got the “memberUid” on group record that can be used.

But this is not helping us in any way.

Can someone on this forum through some light on why apple has not used this member of attribute?
Is there any way we can add this attribute in AOD to get things going?

Any help will be really appreciated in this regards

Thank you
kulthie