Configure "Existing Customer ?" and "Existing Contact ?" Field in Lead Entity

Hello friends, ever face a issue to customize Lead "Existing Customer" and "Existing Account" field available in Lead Business process flow.

Both fields are available in BPF(Business process Flow) and you can enter data to those fields and update the record.

Now try to add those fields in Lead entity form to customize them so your first step would be -->  Go to form and add the field from "Field List" in Field Explorer section in right hand side.

But in this case you will not find these fields in "Field List" with name "Existing Customer" and "Existing Account".

This is because Fields name are
ParentContactId and ParentAccountId

.
It's kind of confusing because different display name in BPF and in entity form.
Hope this help.