[FourtySeven]

How do Mary and the saints listen to perhaps millions of prayers at the same time? Now that they are in heaven do they now have the attribute of omniscience? Because God has this attribute we know that he can hear and respond to millions of simultaneous prayers. But do Mary and the saints have this same ability?

You may find this article useful; note the section "Overlooking the Obvious" for a direct answer to your question above.

[Binghamton_native]

"This does not imply that the saints in heaven therefore must be omniscient, as God is, for it is only through God’s willing it that they can communicate with others in heaven or with us. And Boettner’s argument about petitions arriving in different languages is even further off the mark. Does anyone really think that in heaven the saints are restricted to the King’s English? After all, it is God himself who gives the gift of tongues and the interpretation of tongues. Surely those saints in Revelation understand the prayers they are shown to be offering to God."

The above is an appeal to what 'must be' if the necessary conclusion is to be reached. We still have no more 'evidence' that such is the case.