SSRS 2014 - Force Link in Subscription to Include Default Parameters

am trying to use the SSRS subscriptions to generate an email to
include a link to a report. The email should contain a URL of the
form:
web link looks like <server-name>/reportserver?/Reporting/MSSReport&reportDate=11/11/2008.

As you can see, the URL contains the “reportDate” parameter that
allows SSRS to generate the report for the current date (i.e. the date
of mailing).

I would like to use the report’s subscription schedule to generate
this email on a weekly basis. E.g. the email send out the next time
would be:
web link looks like <server-name>/reportserver?/Reporting/MSSReport&reportDate=11/18/2008

If I setup the reportDate parameter to use a non-queried default value
of “=Today” and then configure the report subscription to use this
default value, unfortunately, the reportDate parameter is hidden and
is not included in the report URL link. If the email recipient clicks
on the report link today, they get the correct report. But if they are
away from work and only click on the link a week later, they get the
report for that day and not the day that the email was originally
sent.

Is there any way to force a default parameter to appear in the email
link?

Alternatively, if the “Use Default” checkbox is un-checked for the
report subscription, you can enter a date that *is* included in the
report URL, however the date used is static and doesn’t role forward
for the next week.

Thanks for you help