how to get flex relate field value in process email template

Dear All,

Can anyone suggest, how to get flex relate field value in process email template.

We have one custom module as "<X>" and in Task record in "related to" field we have selected parent as "<X>", but we are unable to get value of the same in Process email template of Task module.

Also, relationship not showing in Process email template for module  "<X>".

Thanks,

Shreya