ieee membership discount on overlength manuscripts Does IEEE journals of signal processing society (like IEEE Transactions on Information Forensics and Security) consider a discount on overlength page charges for IEEE members?
If so, what is the rate of the discount? Should the corresponding author be an IEEE member or is it possible to receive discount by membership of co-authors?
I have heard that if the charges paid by the institution, it would be reduced from 220$ to 110$ per page. Does the membership discount considered for the overlength paid by institution?(I mean a membership discount on 110$, not 220$).
As far as I know, institutions can pay by the grant of the authors who are professors not students, is it possible to reduce the fee to 110$ by ieee rule explained above (if any!) rule by institutional paying (possibly by the grant of professors), then receive a membership discount from ieee by the student as a member?(I am not asking about institutional rules, I am asking that if there is a kind of double discount in ieee rules)
If more than one author be an ieee member, is it possible to receive the added rate of discount?
I believe there is confusion about what the charges mean. Generally, IEEE has two types of page charges:

Voluntary Page Charges
Overlength Page Charges

In 2020, for IEEE Transactions on Information Forensics and Security, the voluntary page charge rate is $110, while the overlength page charge is $220 — which correspond to the numbers in your question.
However, the meaning of these charges is very different.
Voluntary charges – are actually voluntary. They are not obligatory, usually paid by the institution, and help IEEE to offset some of the expenses incurred in publication.
Overlength charges – are different. They have to be paid for all submissions exceeding X number of pages (X=6 and X=10 for short and regular papers in IEEE Transactions on Information Forensics and Security, respectively). This small note from 2004 might explain things a bit more elaborate; I simply was not able to find the relevant page on the IEEE site directly.
I have never heard of a discount on overlength charges. Often, these charges are paid by the advisor from a grant. I once paid the charges myself as a student when I was in transition between affiliations.
With all that information, it is highly unlikely that you can get the charge lower than $220 pay page over the limit. However, in some circumstances (the reasons have to be very serious), I believe IEEE can waive the charge altogether.

Disclaimer: I serve as a Vice-Chair of Membership and Benefits Committee for IEEE Antennas and Propagation Society; however, this answer is not within my direct area of expertise — thus, posted solely as my opinion as an individual familiar with IEEE practices.