In Odoo-13, in my custom module src/user/membershipzsb, after having created a new qweb (web-layout): portal_my_details_zsb which inherit the Base-View portal_my_details (view id:421), After having created a new qweb (web-layout): portal_my_details_zsb which inherit the Base-View portal_my_details (view id:421) to add 2 input fields (phone_pro and email_pro) in the original form.

And after having updated this custom module, its new html input fields are displayed right on the website page (/my/account).

But in Multi-Website context, when I use the WebEditor to customize this page, a new Base-view is created portal_my_details[mywebsitename] (view id: 7834) which has the same view-key as the original one (view id:421 : portal.portal_my_details) and therefore override this original one and its inherited view (from my custom module).